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  #1  
Old Sat 10 October 2009, 14:10
Atifeh
Just call me: Nader
 
Tehran
Iran
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Experimental hybrid MechMate – Tehran, Iran

Hello Gerald and all,

In my opinion MechMate is not a mere CNC machine. It is a way of thinking, solving problems and widening the horizons of learning. It is a concept with a design philosophy behind it.

Many have build the MechMate and enjoyed its building and working. My perspective differs though. I enjoyed the design. I tampered with the design to fit to my shortages and found out that I was altering and redesigning it, with inspiration from its own design.

I was here 3 years ago when a machine took almost a year to build, but now I am sure we can arrange a contest for who could make a MechMate faster? And you will see it will be operative within 6 weeks. My point is: this design is proven, is working and running business, therefore there is no need to alter it or to introduce a new design for it. And if there is, no one better than Gerald himself can do it. Alterations that I have made were only out of necessity.

With this prologue I would like to share my experience on building an altered or ďhybridĒ MechMate, as suggested by Brian and John with thanks to John, Irfan and Brian for their encouragement.

Originally, it was my log of the work done. I have made some changes. You might find some descriptions redundant, outdated or even irrelevant. Thatís because they slipped my eye during editing. There are a lot of pictures which I did my best to reduce their size to an average of 60-70kb. I wonder if my remaining quota will suffice for all of them.
.
.
.

Although it has been 3 years since I registered in the Mechmate forum, I did not have the opportunity to make one. The reason for such a long period of delay were numerous. There were a multitude of limitation, acquiring parts was the major problem, specially the laser cutting parts and a precision bending shop to provide me with the main parts and a CNC machine shop to provide me with the v-grooved rollers. These took me a long time to survey without any result.

It seems to me that finishing this project might bring some confidence to those who are more or less in my situation, i.e. limited access to financial resources, technologies or parts and equipment. Over 11000 people have joined the MechMate community, while about 40 machines have been numbered.

My aim was to make a 4 axis machine capable of 1250x2200x250 mm working envelope and 500 mm diameter for circular objects. I intended to make it to produce: foundry patterns, PU and fiber glass moulds, small wooden wind turbine blades, model aircrafts and similar products.

Limitations:
Without access to laser cut parts I had to redesign the gantry and the carriage. Fortunately for the carriage linear motion part, there were two other designs in the forum which I could use, although it was also designed to sit on MechMateís carriage design. Therefore the Z axis was based upon size 45 linear guide and rail ( ABBA BRH45AL).

Luckily, Rick from Superior Bearing was very cooperative and I could get the bearings through a friend in the US.

Oriental Motors are not available here but there is a variety of Chinese and Taiwanese stepper motors. I have to build timing belt reducers as well.

There is yet another limitation. My workshop is small and I can not move heavy objects like a 180mm U channel around it, therefore I had to improvise another method for the beams.

The spindle will be a 220V, 3ph., 2kW, ER20 collets, Turkish made (Arel), which is less than half the price of ELTE. For VFD, a DELTA type E was recommended.

The controls will be remained to be decided. I am still chewing on the choice of bipolar or unipolar connection. Either I will use my own made unipolar half stepping boards, or I might get available Chinese microstep drivers. The breakout board I shall make myself.

The structure will be built in modules which would be assembled with fasteners. The structure comprises 4 segments of frame which will be bolted together.
The machine was designed and drawn in MDT6. Here are some images of it.

view1.jpg

view2.jpg

Below pictures show the design of the gantry and the carriage. I would appreciate any comment or suggestion about this design.

view3.jpg
view4.jpg

The structural steels used in this project are: U-channels 80mm, square tube 60x40x3 mm, 100x50x2.5 mm and 40x40x2.5 mm and iron angle 63x63x6 mm and 50x50x5 mm.

I started off by making other assemblies rather than the frame.

The reducers:
Timing pulleys are 25mm wide M5 type, 24 and 72 teeth. The reducers does not have a swing hole but the pivot is made of bronze bushing. There are two makes, one for X and Y axes and the other for the Z axis.
Made some patterns with a small CNC that I made 4 years ago:
reducerpatterns.jpg
Took them to an Aluminum foundry:
reducercastings.jpg
Machined them on my drill press equipped with a XY table:
reducermachining.jpg
Here are the machined parts
reducermachinedparts.jpg
And here are the assembly stages:
reducerstages01.jpg
reducerstages02.jpg
reducerstages03.jpg
reducerstages04.jpg
reducerstages05.jpg
reducerstages06.jpg
reducerstages07.jpg
reducerstages08.jpg
reducerstages09.jpg

And the finished reducers:

3 used for X and Y axes.
reducerXY1.jpg
reducerXY2.jpg
reducerXY3.jpg

1 used for Z axis.
reducerZ1.jpg
reducerZ2.jpg
reducerZ3.jpg
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  #2  
Old Sat 10 October 2009, 14:34
Atifeh
Just call me: Nader
 
Tehran
Iran
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Cutting the rails:
This is the setup I used for cutting the rails. I used my 800W Makita mini grinder and the mounting plate was made to its proportions.
railcuttingfixture.jpg

Setting up for cutting:

railcuttingarrangement1.jpg
railcuttingarrangement3.jpg

Adjusting the height:
cuttingheight.jpg


With this rail cutting fixture each disk (Chinese made), cuts about 5520 mm of rails and shrinks to around 65 mm in diameter.
cuttingdisk01.jpg
cut.jpg

I had to make some fixture for grinding the rails, so I thought of giving plasma cutting a try. I edited Geraldís drawings in order to make the holes 2 mm tighter so that I could drill through the holes to their nominal sizes. The picture shows as-cut quality of plasma cutting. As mentioned minor through hole drillings and filing were required to clear the holes but the set works really fine.
plasmagrindingfixture.jpg

Now I have bought a dedicated 850W Chinese grinder for this job.

This is the grinding arrangement:
bevelling.jpg

I did not have a successful experience using grinding disks. It might be the quality of the disk I use or my faulty way of grinding. After a few minutes of grinding the disk face became smooth and shiny and metal removal dropped to nil, while the grinding surface of the rail became discoloured due to excessive heat. Any idea why?
I found out that using grit 36 sanding disks were more efficient. The noise level is much less and the grinder works cooler.
sandingdisk.jpg

This is the sanding disk after successfully grinding 8800 mm of rails, both sides.
depleteddisk.jpg

An annoying problem: is the development of a groove on the contact surface of the height adjustment screw with the rail (shown below) which forces one to change these screws and readjust the height periodically. It gets worse since I have to index it by 90 degrees which on a M10 screw will be 1.5/4=0.375mm. I replaced the screws with high strength steel screws. The grooves were somehow less but they still exist.
grooving.jpg

Has anybody came to a solution for this? I thought of threading an oil hardening steel rod and then heat treating it to about 40 Rc but I suspect the other way around might happen, i.e. the screw scratches the rail down. Maybe phosphorous bronze or copper beryllium could be used?

Here is the quality of the surface using grit 36.
grindingquality02.jpg

I also used grit 80 sanding disk to obtain a smoother finish. The finish was remarkable but due to the fact that minute feeds should be imposed on the grinding set, the process is long.
Manual sanding with Grit 220 ordinary sandpaper and kerosene as surfactant, virtually yielded a mirror like surface which reduces the rolling friction and I believe would suffice, therefore I dropped the grit 80 process. Of course the deep lines created by grit 36 sanding disk will not be removed by this process but I believe they are of no importance.

Everything gets magnetic.
magnetic.jpg
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  #3  
Old Sat 10 October 2009, 14:50
Atifeh
Just call me: Nader
 
Tehran
Iran
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The carriage:
The design is simple and self explanatory.

carriageparts.jpg
carriagedetail1.jpg
carriage1.jpg
carriage2.jpg
carriage3.jpg
Yplate1.jpg
Yplate2.jpg
Yplate3.jpg

Making the gantry:
I was wondering how could I bolt the rails on the beam while both ends of the beam are sealed? So I came up with this idea. I drilled through 3 of the holes on the gantry beam. Took 3 M8 rod screws about 150 mm length and passed it through the nut plate. Whenever I want to assemble the rails, I would insert the rail in the corresponding holes, lift up the nut plate, secure other screw, take the rod screws and then bolt these three. Detaching the rail will be in the opposite sequence.
railYholemarkup3.jpg
beamstages1.jpg
beamstages2.jpg
beamstages3.jpg
In order to get suitable parallelism between the end plates of the gantry I used a method which you have all seen in http://oneoceankayaks.com/madvac. I named it ďresin paddingĒ (as I donít know the exact name of the process). The compound used for this process was self made and is very reliable and cheap. If there is any interest, I can describe the whole process and materials used. Of course various brands are available. For example I found Devcon liquid steel B, the price of which was out of my league.
beamstages4.jpg
beampadding1.jpg
beampadding2.jpg


This is the gantry and the carriage mounted (without the Z assembly)

gantry.jpg
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  #4  
Old Sat 10 October 2009, 14:52
Atifeh
Just call me: Nader
 
Tehran
Iran
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IT IS GOING TO BE COMPLICATED.

Today is March 20th, 2009. I was not satisfied with the design of the gantry. There is nothing wrong with it, but it didn’t capture me.

I TEMPORARYLY SUSPENDED THIS PROJECT AND STARTED ANOTHER ONE.

From now on you will see the second machine which is more like a MechMate except for the carriage. Afterwards I will return back to this machine.
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  #5  
Old Sat 10 October 2009, 15:07
Atifeh
Just call me: Nader
 
Tehran
Iran
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Machine #2

As I said before I was not happy with the previous gantry, I was wondering if I could use the original MechMate gantry but with the modified carriage.

We have 2 weeks of our new year holiday, so I converted Geraldís drawings to 3D and played around with it to see how it could be managed.
I did some changes on the parts in order to produce them with plasma cutting.

The product will be a 3 axis machine with 1900x3680 mm envelope to cope a full board of MDF and with a vertical movement of about 100-140 mm.

The gantry is the same as MechMate design but the carriage is still different, hence laser cut parts were unavoidable to use in the original MechMate carriage design. The carriage will be identical to the previous make.

Motors are PK296A2A-sg7.2. I got them through someone visiting Malaysia.

The structure will be built in modules which would be assembled with fasteners. Aside the main and table beams, the structure comprises 4 segments of frame which will be bolted together.

Untitled-4.jpg
Untitled-5.jpg

Below pictures show the design of the carriage. I would appreciate any comment or suggestion about this design.

Untitled-1.jpg
Untitled-2.jpg

Structural materials:
The main structural steels used in this project are: U-channels 140 (for the main beam) and 80x40 mm for the table, square tube 40x40x2.5, 60x40x3 mm and 100x50x2.5 mm and iron angle 63x63x6 mm for the rails and 50x50x5. I bought the steel for both machines.

My intention was to sandblast all the structural steels even before cutting and sizing them, so that I could get a good surface for scribing and later painting, which turned out to be time consuming and excessively expensive, therefore I stuck with wire brushing and grit 36 sanding disks. Small parts and also the fasteners are phosphatized in the workshop (itís easy) for preservation and better surface for painting. Here are the parts stacked in trolleys (my current workshop is pretty small and a lot of displacement is inevitable).

partsracked01.jpg

Plasma cut parts:
So far I have provided the motor plates, stiffener closures and the carrier plates by plasma cutting. In some cases I had to change the drawings to undersize the holes so that they will be drilled through later to the actual size. Deburring and finishing, whenever necessary, were done with grit 50 sanding disks.


Printed 1:1 drawings are bonded to the parts, center pinned and drilled on a drill press.
plasacutparts02.jpg

A blank and other drilled parts.
plasacutparts01.jpg

Quality and defects of plasma cuts. It is more profound in thin sheets.
plasmacutquality.jpg
plasmaother1.jpg

Other plasma cut parts.
plasmaother2.jpg
Picture A100.jpg


A REMINDER: if you do have access to laser cutting, do NOT try plasma cutting or even waterjet. It is not worth the time consumed and the quality attained. Remember: under no circumstances plasma cutting is a cheaper alternative or a solution or a substitute for laser cutting. It is like Charlie Chaplinís gold rush movies in which they were short of food and cooked and ate their leather shoes and laces. Now, the leather shoe is the waterjet. For plasma, try plastic slippers!
My approach to plasma cutting was only an act of desperation!
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  #6  
Old Sat 10 October 2009, 15:20
Atifeh
Just call me: Nader
 
Tehran
Iran
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The rails:
63x63x6 mm angle iron were used for the rails. I managed to cut both X and Y rails but grind the Y axis rails which are shorter. I will grind the X axis rails when assembled on the main beams.

Markup for drilling the X rails:
markupXrail.jpg

A 2 meter steel ruler that I bought recently proved to be a very useful tool and better than tape measures. Markings will only give the longitudinal position of the holes. The lateral position of the holes were scribed for each hole against the reference edge.

Preparing the nutplates for gantry beam and Y rail markup and drilling.
nutplate1.jpg
nutplate2.jpg

I found this tapping adaptor, lying around in a tool shop and bought it very cheap. Bought a Chinese chargeable drill, removed the chuck and equipped it with this tapping head. It is powerful enough to tap up to M8, pass 2 and 3 taps. Pass 1, it cannot manage.
nutplate3.jpg

Transferring nutplate holes to Y rails:
markupYrail1.jpg
markupYrail2.jpg

Transferring nutplate holes to gantry beam.
markupgantrybeam2.jpg
markupgantrybeam1.jpg

The previous cutting fixture was not comfortable to work with, mostly due to the nasty fume of burning MDF resulting from the sparks. I made another one which now its holes match Geraldís cutting/grinding fixture. Also lined the circular part with a piece of Aluminum strip. No more fumes.

I tested the upper part of Geraldís rail grinder for cutting This setup only allowed me to use the cutting disk up to around 85 mm in diameter since I used 63 mm angle irons. I made another plate for the new fixture, without the 45 degrees flap so that I can go down to 65 mm.

Grinding (actually sanding) the surface of the cut face of the rails with the new fixture.
fixturenew2.jpg
fixturenew1.jpg
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  #7  
Old Sat 10 October 2009, 15:55
Atifeh
Just call me: Nader
 
Tehran
Iran
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The main beam:
I chose U140 over the U160 and bigger sizes for the main beam, the reason was its weight and complexity of movement and displacement in my workshop. The drawings show that I still have about 140 mm of Z travel but I have to lower the position of the X axis e-chain supports.

The lower side of the beam which will sit and bolt to the frame was scribed and drilled before cutting the 45 degrees end cuts.

End cuts done with the remainders of the cutting disks from rail cutting.
beamendcuttingangle.jpg

Beam end plates cut and bent.
beamendbendplate.jpg

Stages of transferring the X rail holes to the main beam:
beamholetransfer01.jpg
beamholetransfer02.jpg
beamholetransfer03.jpg
beamholetransfer04.jpg
beamholetransfer05.jpg

The center finders are made by myself. They are plastic mould ejector pins which are precise, extremely hard and durable, comes in different lengths and cheap. I grip it in a drill press chuck and grind it from below to leave a 1mm cone on its flat surface. Have never re-sharpened them in the last 4 years and are still working.

beamholetransfer06.jpg
beamholetransfer07.jpg
beamholetransfer08.jpg
beamholetransfer09.jpg

Drilling the beam
mainbeamdrilling.jpg

Here are the beams drilled, deburred and finished.
beamfinished02.jpg
beamfinished01.jpg
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  #8  
Old Sat 10 October 2009, 16:46
Robert M
Just call me: Robert
 
Lac-Brome, Qc
Canada
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Nader, Iím SpeechlessÖ.
Maybe took 3 yrs to get there, but NICE prep & work so far !
We should open a sub-group for those of us taking +/- 3yrs to start a built

Many thanks for sharing you zillions photos, it is inspiring for me, a guy who as a very hard time with steel, weldingÖ.darn, Iím a woodworker who is getting a new passion for steel too

Well, can only add congratulation and canít wait to see your hybrid finished.
Amicalement, Robert
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  #9  
Old Sat 10 October 2009, 20:13
jehayes
Just call me: Joe #53
 
Whidbey Island, Washington
United States of America
Nader: Great job! Thanks for the excellent photos. Can't wait to see the machine assembly! Joe
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  #10  
Old Sat 10 October 2009, 20:20
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Nader, great history! Your attachment quota has been increased.
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  #11  
Old Sat 10 October 2009, 21:02
riesvantwisk
Just call me: Ries #46
 
Quito
Ecuador
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Great job indeed and VERY inspiring and some good ideas aswell.. I just realized I could have done some things better, I think I am fine still.. but with your pictures and ideas I think I should have done the same..

great job!
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  #12  
Old Sun 11 October 2009, 02:19
Polder48
Just call me: polder
 
Edam
Netherlands
Nader, thanks for an inspiring story of your build. Great pictures and a lot of inginuaty involved. Keep on going!

marveless job!

cheese Polder
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  #13  
Old Sun 11 October 2009, 04:13
isladelobos
Just call me: Ros
 
Canary Islands
Spain
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Very accurate work
Well taking pictures
Nice ideas.
Thanks !!!!

bandwich.jpg
A lot of bandwich charging this web thread
Max:5mb/ps
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  #14  
Old Sun 11 October 2009, 05:09
MetalHead
Just call me: Mike
 
Columbiana AL
United States of America
Great work - I am amazed everytime I read this forum. You all are great. I'm a slow starter also and still collecting parts and dividing time on other projects. But I will build a MM for sure !!!

Again great build!! And Great work.

I think steel is a great medium and those who can even scratch the surface (no pun intended) building with it always amazes others !!!
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  #15  
Old Sun 11 October 2009, 06:42
jhiggins7
Just call me: John #26
 
Hebron, Ohio
United States of America
Nader,

Great work, comprehensive build history, inspirational build!

I think you have captured the very essence of the MechMate way.

Good luck to you as you finish your MechMates. Keep up the exceptional work. Gerald has increased you allocation, so please keep documenting as you go.

If we can help you please don't hesitate to ask.

Thanks for sharing your inspirational build.
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  #16  
Old Sun 11 October 2009, 07:05
Atifeh
Just call me: Nader
 
Tehran
Iran
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Guys, thanks all for your kind words and support, glad to tighten a small M2 screw in this forum. After all it was most your ideas.

Robert, Thanks for your interest and kind words. This might not sound so good, but I have to admit that we are all drifting from wood working to machine building! I for one!

Nader
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  #17  
Old Sun 11 October 2009, 07:13
Atifeh
Just call me: Nader
 
Tehran
Iran
Send a message via Yahoo to Atifeh
Table cross beams:
A drilling template is made so that the hole pattern on all the table U channels be reasonably identical.
tablechannels01.jpg

The indents of the center finder (as seen in the picture below) will give the longitudinal position of the holes. The lateral position is scribed for each hole cross a reference edge. After I drilled all the holes I realized that this was a mistake. I should have drilled the holes all along the template to attain a straight line.
tablechannels02.jpg


This is a simple template I use to mark the 60 degrees cutting of the table U beams:
u80endtemplate.jpg


Here are the table channels bored, deburred, cut and finished. The holes next to the outer holes are drilled through both upper and lower wings of the U80 beams. I am using the two guide through holes concept on the edge side of the spoil board as previously devised by Sean (SMReish). I intend to tap the other 4 middle holes right on the channels so that fixing the spoil board will be done from above. I assume the other way around would be that someone lies under the table and secures the wedge washer and nut, while another one fastens the bolts from above.

tablechannels03.jpg
tablechannels04.jpg

I will FAST FORWARD to the assembly stage of the finished machine so that you can see how the drilling template is used to locate the matching holes on the MDF board. Please note that the outer holes on both sides were marked from below with an 8 mm center finder and drilled in order to obtain the fixed points. Fortunately, the total job was a success, although a number of holes were about 1-3 mm off their centers, which was due to the U80ís cambers resulting from the above mistake, which were corrected. Countersunk 8x30 mm screws were used to secure the lower MDF board to the table beam..

MDFmarking1.jpg
MDFmarking2.jpg
MDFmarking3.jpg
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  #18  
Old Sun 11 October 2009, 07:38
Atifeh
Just call me: Nader
 
Tehran
Iran
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Frame:
Making the legs:
The vibration dampers had only one nut. I had to buy a M16x1.5 mm tap to provide a positive locking for the nut.
leg1.jpg
leg2.jpg
I bought a lot of cheap HSS tool steel strips and blocks, only to use them as shims while levelling the frame. They are 200m long and when halfed provided a lot of shim plates with a lot of combinations. Their tolerences are within 0.1 mm. These were the sizes I bought: 2x10, 3x10, 4x10, 5x10, 6x10, 8x10, 10x10, 20x20 and 25x25 mm. you can see their use in the below picture.

levelling.jpg

Here are the stages for mounting,tack welding and final welding of the frame:
framestages01.jpg
framestages02.jpg
framestages03.jpg
framestages04.jpg
framestages05.jpg
framestages06.jpg
framestages07.jpg
framestages08.jpg
framestages09.jpg
framestages10.jpg
framestages11.jpg
framestages12.jpg
framestages13.jpg
framestages14.jpg
framestages15.jpg
framestages16.jpg
framestages17.jpg
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  #19  
Old Sun 11 October 2009, 07:48
Atifeh
Just call me: Nader
 
Tehran
Iran
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Gantry

The carrier plates were cut blank by plasma cutting, the holes were transferred by scribing and then drilled. The bean shaped or elongated holes were shaped by filing.
gantryparts.jpg

Preparation for assembly:
gantrypreparationfor weld.jpg

I checked the parallelism with a well levelled table and laser square.

gantryparallelism1.jpg
gantryparallelism2.jpg

Here are the sequences of welding the gantry:

gantryweldsequence1.jpg
gantryweldsequence2.jpg
gantryweldsequence3.jpg
gantryweldsequence4.jpg
gantryweldsequence5.jpg
gantryweldsequence6.jpg

The finished gantry:

gantrydone.jpg

This was my first try on weld straightening. There was some 15 mm of camber. Went off real good. I hope it is not the beginners luck!

gantrystraightening1.jpg
gantrystraightening2.jpg
Attached Images
File Type: jpg gantryweldsequence7.jpg (43.3 KB, 2962 views)
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  #20  
Old Sun 11 October 2009, 07:53
jhiggins7
Just call me: John #26
 
Hebron, Ohio
United States of America
Nader,

Nice work, great pictures. Love the castor idea...portable but stable once it is relocated.
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  #21  
Old Sun 11 October 2009, 07:56
Atifeh
Just call me: Nader
 
Tehran
Iran
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The carriage:
Here are the stages of making the carriage:
carriagestages1.jpg

carriagestages2.jpg

carriagestages3.jpg

carriagestages4.jpg

carriagestages5.jpg

carriagestages6.jpg

carriagestages7.jpg

carriagestages8.jpg

carriagestages9.jpg


A proof of negligence:
While in MDT, I did not account for the thickness of the double sided tape. Also I should have mounted the 30 tooth pinion instead of the 20 tooth. The result was that the motor assembly did not have enough room to slip inside the rack. I had to re-drill and re-file the bores.

defective1.jpg

I used KR-32 idler needle bearings instead.

idler.jpg

Another hole placement miscalculation.

defective2.jpg

The pinions:
There were only module 1 pinions with 22 and 26 teeth available, both of which had a hub thin to accommodate the 12.7 mm motor shafts. I ordered a machine shop to make 4 each of, 20, 22 and 30 teeth pinions with enough hub to be drilled. He made them on a Chinese milling machine with teilekopf, amazingly precise. Cost me around $10 (equivalent) each.
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  #22  
Old Sun 11 October 2009, 08:47
Atifeh
Just call me: Nader
 
Tehran
Iran
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Microswitch supports:
Mechanical microswitches are a lot cheaper than proxy switches. In addition I could not make the carriage arrangement of MechMate which had built in locations for the proxy switches, so I chose to use mechanical microswitches. Improvisations were required for their arrangement and room for adjustment. The following pictures show these arrangements:

Limit switch for marking the end of table in X direction. This was a bad choice. I should have placed it on the other side. I wanted the Home side to be uncluttered with these devices. Will review this on the first machine.
swXL1.jpg

Parts required for the Y axis Home/Limit pair of switches assembly.
swYHL1.jpg

Marking the place for the Y axis Home/Limit pair of switches.
swYHL2.jpg

Y axis Home/Limit pair of switches arrangement secured.
swYHL3.jpg

The adjustment distance:
swYHL4.jpg

Closeup of how it works:
swYHL5.jpg
swYHL6.jpg
swYHL7.jpg

Y axis Home/Limit pair of switches and the other end limit switch.
swYHL8.jpg
swYL1.jpg

Parts required for the X axis Home switch and the autosquare end assembly.
swXH1.jpg
swXH2.jpg

Z axis has also a Home/Limit pair of switches with an adjustable height slide.
swZHL1.jpg
swZHL2.jpg
swZHL3.jpg

This was the last part made. What would happen if the end limit switch malfunctioned and there were no soft limit lamp on?
Xstop.jpg


Echains:

Details of Y axis Echain:
echainY.jpg
echainYsupport1.jpg
echainYsupport2.jpg
echainYsupport3.jpg

Details of X axis Echain:
echainXsupport1.jpg
echainXsupport2.jpg


A design problem:
I think there is a glitch with the arrangement of the X Echain. You see, it is convenient to park the gantry during idle times at HOME position. One reason would be the loading of the machine which is from the front. When parked at home, the Echain rolls up from its support and gets suspended. I noticed that my Echain sags under the weight of the cables. If it is indexed 180 degrees, then while gantry is at rest or idle position, the Echain will rest on the support, rather than be suspended. Of course it is not an easy task. A lot of cosiderations should be reviewed, for example the cable routes from Y Echain and the sweeping characteristic of the X2 motor. A lot of laser parts should be revised then. Please comment on this.
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  #23  
Old Sun 11 October 2009, 08:48
Atifeh
Just call me: Nader
 
Tehran
Iran
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Next will be: The Assembly, Control Panel, Cabling and the final Touch Ups.
They I shall return to the First machine.
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  #24  
Old Mon 12 October 2009, 03:58
Atifeh
Just call me: Nader
 
Tehran
Iran
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The assembly:
Painting:
Two part Epoxy primer and paint were used. I gave 48 hours interval before applying the next layer and then tested the quality of the paint adhesion with the scratch and tape method. The adhesion quality was outstanding, but the quality of the paint not so. Mainly due to the local weather phenomenon of suspended dust which took about a week or so to clear.
Each individual part was primered and painted.

AfterPaint.jpg


Squaring the machine when you are alone and nobody is to help.
Square Alone1.jpg
Square Alone2.jpg

Aligning the rails:
RailAdjustment1.jpg
RailAdjustment2.jpg

These are the stages of assembly:
assemblystages1.jpg
assemblystages2.jpg
assemblystages3.jpg
assemblystages4.jpg
assemblystages5.jpg
assemblystages6.jpg
assemblystages7.jpg

Installing the rack:
The rack was almost 4000 mm. twice it broke from the weld joint. At last I preheated the joining parts with a torch to about 400 degrees C, checked it with thermochalks, and then commenced welding. This time it held.
I suspended the rack by the two end screws and some suspended wires, washed the contact surface with aceton and placed the tape, lifted the top paper cover and carefully raised the rack.
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  #25  
Old Mon 12 October 2009, 04:25
Atifeh
Just call me: Nader
 
Tehran
Iran
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Control:
I finally settled on unipolar wiring. I opted for the speed. Bought 4 microstep 0.5-6A max.80V unipolar drivers from local suppliers (originally from: www.bsjd.com). I tested them and seems fine for the price. They are opto isolated (something I donít like) but they claim it works up to 200kHz.

Ordered a 220/28 VAC transformer to get around 38 VDC. The capacitor is a 20,000 uf 80V.

The breakout board, I made myself. It is a buffered board using 74HC541 (around 35mA buffered output). I just read the logic diagrams of PMDX-122 in their manual and mimicked its logic. The circuit is simple and no ENABLE used for charge pump. Instead I allocated 4 pins for relay devices which I donít know what Iím going to do with them?

Honestly, I donít see any virtue with this charge pump idea. Do you really need to start your machine prior to the computer? I always start the computer, then the Mach and then start the machine. Whatís wrong with this procedure? And just for the kick of it, I once started the machine, then the computer. Nothing except for some grumps and growls happened. They are exaggerating this feature that without it your gantry might rampantly ramble around and such, I suppose.

The breakout board was designed as a single sided board with PCBExpress (www.pcbexpress.com). I then printed it in pdf format and had it printed on film. Then used laminate sheets on ordinary PCB copper boards, exposed it to two cheap 4W UV lamps that are used to identify fake bills, developed it in Na2CO3,acid wash it and made it. The board totally populated cost me around 5$ and works flawlessly.

I also used a small 220/12V 20VA to provide 12 VAC to the Estop and limit circuit and a small 5/12 VDC 1A board which would feed the breakout. The breakout feeds the drivers. The 5/12 VDC could also provide power for future relays.

Here is my wiring diagram for the live part. Please note the use of 12VAC for the Estop and limit circuits. It is far safer than 220V.

The brown/blue lines are the 220VAC PH. and NULL and the green/orange are the 12VAC live and neutral lines.
livediagram.jpg

I would suggest visiting this site: http://www.veppa.com/ekts/
There is a free program that lets you play with different relays, contactors, motors, switches and other electrical parts. You can then simulate your circuit and every fault will be revealed. It is designed by a university professor in Turkey as an educational aid. The interface is not much of a fun (as Livewire) and needs some patience, but everything practical I know about designing electrical circuits owes to this programme.

I believe the next stop for us wood workers who are becoming machine builders, would be migration into the realm of electronics! So shape up!

The box stages:
I bought a panel which had only 3 holes at the bottom side, before drilling holes in it I decided on my priliminary layout.
panelstages1.jpg

Next I drilled holes with Morse round cutters:
panelstages2.jpg
panelstages3.jpg
panelstages4.jpg

This idea of auto air filter by Rad racer was very nice.

Stages of populating:
panelstages5.jpg
panelstages6.jpg

Please note the grounding hub next to the cooling fan.
panelstages7.jpg
VDCsection.jpg

The driver and breakout board section.
drivers_bob.jpg

Here is the control panel:
panel6.jpg

I took extra care to divide the control panel to different zones to minimize the noise of AC and high current DC voltages on the control 5VDCís. Here are the different sections.
panel5.jpg


What that is not shown are the groundings. Every individual cable shield was grounded to a main hub inside the panel which then left the box to join the main earth cable. 6mm cables were used for grounding.

Here are some pictures of the panel connectors:
panel1.jpg
panel2.jpg
panel3.jpg
panel4.jpg

The VFD runs manually. For the first machine I will use a 0-10V board (remember? This is the second machine).

And for the last, here is the total cicuitary of the panel, except for the interconnections to drivers and breakout board which differs for various makers. Unfortunately the pdf version is only in black and white, but the edrawing copy is in colour (in rar format).

electrical UR11 j.pdf
electrical UR11 j.rar

Grounding:
Dug a hole on a corner of the new workshop which is a basement of a building, about 700 mm deep. The soil was moist in that depth. Picked up a copper strip 6x60x500 mm, drilled at one end and screwed two cable shoed 6mm copper wire to it. Hammered it in the hole so that it went down another 400 mm into the ground. Layer by layer filled it so that in the middle, where the copper strip was buried, I put a mixture of coal and salt, and around it the sieved soil. Then a nylon sheet on top of that so that it will not loose the moisture. I will then occasionally pour some water in the hole to maintain its conductivity. The potential, relative to the NULL line was 6.1 Volts. It should have been less than 5 Volts but to get that, I had to dig deeper which was not possible. I believe that will do.
EarthHole.jpg

For collecting the static electricity that accumulates in the dust collector duct, I use a bare braided 14x1.5 mm copper wire and after isolating it with shrink tubes, screwed one end to the steel structure of the building.

Here are some pictures of the cabling:
cablerouting1.jpg
cablerouting2.jpg
cablerouting3.jpg
cablerouting4.jpg
cablerouting5.jpg
cablerouting6.jpg

Arrangement of the panel:
panelarrangement1.jpg
panelarrangement2.jpg
panelarrangement3.jpg
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  #26  
Old Mon 12 October 2009, 04:35
Atifeh
Just call me: Nader
 
Tehran
Iran
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Different views of the machine.
view1.jpg

view2.jpg

view3.jpg

view4.jpg

view5.jpg

view6.jpg



Trial run:
I bought an ER20 collet, 6 mm and tried some patterns. At 10th microstep there were no stepped cuts in a curved line. The squareness was bad on a single sheet of MDF, about 4mm in 4000 mm which was corrected. I set the speed at 2500mm/min, the Mach frequency is 25kHz. Unfortunately all the pictures of the works were on a camera chip which I have misplaced it somewhere. I will post the works in a short time.



Last words on this machine:

I really had a lot of exciting and good times, specially with works that I have never done before. A list of my favourite operations were:

Straightening the beams and rails by welding.
Cutting the rails.
Grinding the rails.
Finding that there is only one shop in Tehran that has wedged washers sizes 8 and 10 mm, and now I know it.
Paying the cost of a one week leisure tour to Malaysia in a 5 star hotel for the wife, which turned out to be much cheaper than having TNT bring me the PK motors from there!
Mounting a thin 4 meter object with double sided adhesive tape.
Painting with 2 part epoxy paints. 4 years ago I bought some epoxy paints for a job and was wondering why is it named epoxy when it is only in one container and there is no hardener and is no different that other paints?!
Finding out that after 55 years of age, a broken toe could mend in 2 weeks, just by ignoring it and a little rest!
Understanding the correct way of shielding and grounding.

Now, the excitement still continues since I will be completing the first machine which has a fourth axis and since I have 4 more output pins there are a lot of possibilities to use.


Now back to completing the first machine.
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  #27  
Old Mon 12 October 2009, 05:46
Gerald D
Just call me: Gerald (retired)
 
Cape Town
South Africa
Quote:
Originally Posted by Atifeh View Post
Honestly, I donít see any virtue with this charge pump idea. Do you really need to start your machine prior to the computer? I always start the computer, then the Mach and then start the machine. Whatís wrong with this procedure? And just for the kick of it, I once started the machine, then the computer. Nothing except for some grumps and growls happened. They are exaggerating this feature that without it your gantry might rampantly ramble around and such, I suppose.
A real story: We have a general power failure in the town. 20 minutes later one of our staff starts changing the cutter in the spindle. The power comes back on and another guy switches on the control panel again. But the spindle also starts by itself! (Luckily nobody touching it right then, but the spanner/wrench goes flying).

What happened was that the PC took its power from the main supply (not the control cabinet), the PC did an automatic reboot when the mains power came back and this did a false signal to the PMDX before Mach started running.
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  #28  
Old Mon 12 October 2009, 08:42
jessyjames
Just call me: James
 
Reno, Nevada
United States of America
Nader great job on the build thus far. I really appreciate the many pictures that you have allowed us to view through your process of building a nice looking mechmate.

I'm one of those builders who don't really post anything and just gets to building. Maybe those days are over..?

Keep up the hard work. Gerald's design is just outstanding and the knowledge on the forum is just short of amazing..

Keep the pic's coming Nader.

Respectfully,

James
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  #29  
Old Mon 12 October 2009, 14:35
Alan_c
Just call me: Alan (#11)
 
Cape Town (Western Cape)
South Africa
Send a message via Skype™ to Alan_c
Nader

Very nice work and well documented as well - interesting solutions to some of your challenges. In South Africa we have a saying: "'n Boer Maak 'n Plan" wich roughly translates to a farmer always has a solution to solve problems - I think you qualify as an honounary Boer well done.

Alan
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  #30  
Old Mon 12 October 2009, 19:19
domino11
Just call me: Heath
 
Cornwall, Ontario
Canada
Nader,
Thanks for sharing those pictures and the story. Very well done and documented.
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