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  #31  
Old Sun 01 August 2010, 02:20
Red_boards
Just call me: Red #91
 
Melbourne
Australia
Steel arrived.
Boy those 300 x 95 PFC are big and heavy!

Got most of the kitchen table project together. Didn't have wire for linking Geckos and motors. Any recommendations? Shielded or not?

In Shanghai. It's hot and humid but the city is looking great (cleaned up for the World Expo). Shopping for odds and ends tomorrow. Any recommendations on proximity swiyches? Those threads don't seem to have too many conclusive answers that I could see.

Much appreciated.
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  #32  
Old Mon 16 August 2010, 07:31
Red_boards
Just call me: Red #91
 
Melbourne
Australia
Table build question

I was considering starting the table build similar to Fabrica's where he started off with the cross braces bolted to the support board.

Considering that I will be building separate end pieces for a bolt-together assembly:

Should I tack the cross brace structure to the beams so that I can drill them in situ?
Or should I mark and drill the cross brace structure on the beams and square the table during assembly?
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  #33  
Old Mon 16 August 2010, 08:15
Alan_c
Just call me: Alan (#11)
 
Cape Town (Western Cape)
South Africa
Send a message via Skype™ to Alan_c
Red see here how I did mine. If you look back a page or two (here) you will also see how I made the connector flanges.
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  #34  
Old Mon 16 August 2010, 20:10
Red_boards
Just call me: Red #91
 
Melbourne
Australia
Thanks Alan. That's one of the builds I read closely. I have your table assembly sequence referenced in my "Table Build" notes. I remember your table ends were a trifle out but you were able to 'persuade' the bolt holes into alignment.

My thoughts were to get the beams parallel using the cross structure before bolting the ends into place, but if I bolt the ends on first, then I can square the table with the cross structure. I guess it's 6 of one, half a dozen of the other.

PS: I just wish I could emulate the quality of your build. I try to remember to measure twice (three times in my case), plan twice, think and then do. My natural tendency is to do and then fix mistakes. At least that's possible with a steel table. I shudder to think what might happen with wooden base table mistakes.
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  #35  
Old Tue 17 August 2010, 00:32
Alan_c
Just call me: Alan (#11)
 
Cape Town (Western Cape)
South Africa
Send a message via Skype™ to Alan_c
I think the problem I had was caused by tacking the assembly together while bolted then doing the full welding with the loose components allowing the free ends to move about as the welds cooled - If I had to do it again, I would weld it completely before taking it apart.
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  #36  
Old Thu 19 August 2010, 05:27
Red_boards
Just call me: Red #91
 
Melbourne
Australia
Bolt together table question

Alan,
Thanks for your insights.

Another question:
What size bolts for bolting sides to legs?
I'm thinking M12. Looking at various pictures this seems OK, but I'm interested in other thoughts.
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  #37  
Old Thu 19 August 2010, 07:54
KenC
Just call me: Ken
 
Klang
Malaysia
Majority of the screws used in this build are M8 & M12, unless you have more drill bit size then minimum, you can use larger ones.
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  #38  
Old Thu 19 August 2010, 08:28
Red_boards
Just call me: Red #91
 
Melbourne
Australia
Thanks, Ken. That helps.
Just finalising the fastener order so that I can start drilling holes and welding bits.
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  #39  
Old Thu 19 August 2010, 08:37
KenC
Just call me: Ken
 
Klang
Malaysia
Drilling is the most boring part of the build... at least for me...
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  #40  
Old Thu 02 September 2010, 20:15
Red_boards
Just call me: Red #91
 
Melbourne
Australia
Ugly duckling kitchen table project

It's official! Power supply connected to BOB, drivers and motors and things are running. Now on to installing the PMDX-125 /Mach3 configuration file from the PMDX website and learning how to get the computer to driving things. Then on to playing with proximity switches and E-stops while welding and drilling in spare time.

The wiring is a mess, as you can see from the 'photo, but now I can see the benefits of the kitchen table project in helping me plan how to wire a bit more neatly in the control box.
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  #41  
Old Fri 03 September 2010, 06:29
Red_boards
Just call me: Red #91
 
Melbourne
Australia
Installed the XML configuration file for Mach3 from the PMDX website, added and extra output for the second x-motor, reversed the direction of the second x-motor and slaved its output to the first x motor.
Plugged in the parallel cable and tested the e-stop then jogged the motors from the computer.
Took about 1/2 hour total from loading the config file to getting the motors responding to a G-code program.
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  #42  
Old Tue 14 September 2010, 18:05
Red_boards
Just call me: Red #91
 
Melbourne
Australia
Table ends almost done. Have to weld on the flanges so I can bolt them to the legs.

I started cutting the 45 degree angles in the angle braces using a thin disc in my hand grinder. Soon gave that away. Went out and got a cheapish (but OK quality) cut-off saw. Having the piece fixed in the vice and using a 20" blade made cutting the angle braces quick(ish) and vastly more accurate. Well worth the $180!

I also bought a cheapish 140A welder. After agonising about work load, amps, etc., I decided that I could afford $120 to experiment. If it was all too hard then it would be sold on eBay and I'd seek professional help.

It's been fun learning to weld. I take it slow and get everything clamped tight before starting. Having some trouble blowing holes through one piece when there is a gap between the pieces to be welded. Getting better at laying down welds to fill gaps (a result of my hand-held cut-off attempts), but even my "very best welding" is ugly.

To give the machine a break between sticks (small machine will cut out if used continuously), I go drill a hole or cut a piece of steel.

I'm leaving spaces I can weld later when my technique improves, and not grinding back my welds until I'm sure I can get strong thin welds.

Photos of welds censored by the CAUW (citizens against ugly welding - not to be confused with crows that have similar worries!). Maybe later.

Last edited by Red_boards; Tue 14 September 2010 at 18:09.. Reason: Fixed english (twice!)
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  #43  
Old Tue 14 September 2010, 20:31
bradm
Just call me: Brad #10
 
Somerville(MA)
United States of America
Red, my welding may never get pretty. The important piece is to keep trying. Good for you!
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  #44  
Old Tue 28 September 2010, 19:33
Red_boards
Just call me: Red #91
 
Melbourne
Australia
Shopping in China

This is a late report about a trip to Shanghai where I did some shopping. The scale of things is unbelievable, and the range of stuff available astounding. Tricky sometimes to verify quality. PS my wife is Shanghainese, so she really helped a lot describing things and clarifying what I needed - couldn't do it without a translater. But you can find students with passable english (and other languages!) who will guide you and translate for you if you want to try this route.

Some pics:
THE electronics parts superstore. If you can't get it here it probably does not exist. Outside and inside views. 6 floors of stallholders and stores - like a large department store, only with interesting things from bottons to proxy switches to motors chips, cable of every sort and even cable chains.


If you can't find what you want inside the store then the street has hundreds of little stores that specialise in different things (steel, fasteners, bearings, etc.)
Here's some of the goodies I bought. Skate bearings, 50m of shielded cable, proximity switches, connectors and some other odds and ends. I also bought some cable chain that was too good a deal to pass up. We'll have to see whether the quality holds up. Needless to say the prices were a fraction of what I'd pay in Australia.


Interestingly when I went to another computer superstore I found prices to be far less competitive and I could build a computer system in Australia for close enough dollars to not warrant the hassles and risk of having one built there.
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  #45  
Old Tue 28 September 2010, 19:52
domino11
Just call me: Heath
 
Cornwall, Ontario
Canada
Drool..... wipe.... Drool.....wipe. I am jealous.
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  #46  
Old Tue 28 September 2010, 19:58
Red_boards
Just call me: Red #91
 
Melbourne
Australia
Table ends

I got the table ends done.
Haven't ground down the terrible welding - I'm saving that for when my welding is better so I can do some good welds on the clean faces and then grind down the poor welds. Well, that's the theory, anyway!
The legs are bolted on temporarily - they will be part of the longitudinal ladder.
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  #47  
Old Tue 28 September 2010, 19:59
Red_boards
Just call me: Red #91
 
Melbourne
Australia
Cross supports

After some good advice from much wiser and more experienced people on how to tackle my cross bearers, I got to drilling. I'd had some difficulty marking holes right, so Ross suggested I paint the beams with "Mark Out" (a purple paint) so I could score lines with a starp steel spike (scoring pencil?). He also suggested Drilling holes in a template and then using a punch through the holes to mark the hole centres. The pic shows these necessary tools.
The idea was to mark every cross beam accurately, drill the holes and then bolt to the beams. It turns out I had to do the calculations about four times. There are bits of tape on the template and one beam where I marked and drilled (the template) incorrectly. Eventually I got to where I could mark the beam from either end and get the same hole centres.
Then the drilling. Got better at drilling as I went along. Eventually got down from 400 to 250RPM on the 9mm bit and seemed to be getting nice spirals of steel moving from the drill bit. Lots of cutting oil!
Funny, not all the holes lined up when I aligned the beams. Still trying to figure how I missed centres by as much as 2mm!
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  #48  
Old Tue 28 September 2010, 20:22
Red_boards
Just call me: Red #91
 
Melbourne
Australia
Beams squared

After a day of moving these monster beams I figured I should take a break and push computer buttons instead.
The pic shows the setup I have devised. The beams are raised so that I can move the table drill under them and drill for the cross supports.

Getting the beams into position was a mission. I got the first raised and levelled and then got the second raise in more or less the right position. I clamped a cross support to them so they wouldn't topple and destroy something important (like my leg!).
Then I was tired of hefting the darn things alone so I got the car jack out. I struggled for a while to get the beams the right distance apart AND parallel at the same time. You may read this as several hours and a few thousand cuss words.

I already had wooden jigs made with flanges at outside beam width (1240 table + 430mm). My idea was to bang the beams into submission until they lined fitted the jigs at either end, and then clamp it all down.

Needless to say it didn't work that way. One beam was crooked and 20mm out of alignment. That's where the skateboard and broom handle came in (took a while to figure this out). I jacked one beam and put the skate under one end. Then I jacked the other end and put the broom handle under it. I loosened the clamps while supporting the beam from toppling with the table ends. Then it was a "simple" matter of turning the broom to move the beam forward and aft.

After a while it was lined up and could come off the wheels. A couple of short sharp blows with the 5lb hammer and I got it slid sideways to the correct width. Clamped down a couple of cross members and then got the jack out for some final levelling using end grain wedges.

Input, ideas and suggestions welcome. It might save the neighbour's ears for next time. For which I'm sure they will be eternally grateful.

Honey, I know I said it was only for 2 days, but I think It's staying there until I have the holes drilled and legs attached. A week at most, I promise!

Note: I had my fingers crossed.
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  #49  
Old Tue 28 September 2010, 20:36
Red_boards
Just call me: Red #91
 
Melbourne
Australia
A question about beam flanges not at 90 degrees

I notice that the flanges on the beams are not perfectly at 90 degrees - they tilt inwards a bit. Should I try to tilt the beams so that the flange is level (which may prove very difficult) or will I be able to shim the rails to get them level?

While I'm not advocating this, it seems upon reflection that the rails need to be parallel, but if they tilt in a touch it won't dramatically affect the way the vee bearings roll - as long as the tilt is even and not too dramatic? The 60kg y-car surely won't have sufficient leverage over the 28mm of the rails to cause them to fold if the forces transmitted through the vee bearings are not directly downwards?
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  #50  
Old Wed 29 September 2010, 02:53
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
Hi Red

You got some action going on there - well done.
When you find out how those little errors creep in be sure to let us all know! hehe

The rails can be packed level with shims - a few more or less on the inside or outside should correct for the error in the flange.
The rail will remain quite stable once the bolts are done up.
I corrected some twist due to welding shrinkage on the ends of my beams using this technique quite successfully.
The rails need to be 90 degrees to the x beam web so that the rack stuck on the bottom edge mates at 90 degrees to the shaft of the stepper motor and the pinion.
Failure to get this correct means the pinion teeth will not mesh along the full width of the rack.
This is an example of the need to get the relationship correct - http://www.mechmate.com/forums/showthread.php?t=2815

Regards
Ross
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  #51  
Old Thu 07 October 2010, 20:46
Red_boards
Just call me: Red #91
 
Melbourne
Australia
Two weeks and no action. Visiting relatives, work and other stuff getting in the way (finally got to repairing that surfboard with the snapped nose). Got the vee bearings and bushes from Rick at Superior Bearings. The entire process was painless (and more so because the AUS$ is creeping towards parity with the US$!

Picked up an essential item that came highly recommended by the guys at Total Tools. It's a drill sharpener made in Oregon. http://www.drilldoctor.com/. I see them offered for sale in the US on eBay.

Time to get drilling those beams!

Last edited by Red_boards; Thu 07 October 2010 at 20:47.. Reason: got the manufacturer country right!
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  #52  
Old Fri 08 October 2010, 05:04
AuS MaDDoG
Just call me: Tony #71
 
Brisbane
Australia
Red,

You will not be dissapointed with the Drill Doctor, thats what we are using here too, they work a treat!! although I used to enjoy sharpening the drill bits on the old grinder by hand

Cheers
Tony.
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  #53  
Old Sun 17 October 2010, 21:04
Red_boards
Just call me: Red #91
 
Melbourne
Australia
Got to drilling beams this weekend. I'm drilling so I can bolt the cross members in place and can bolt the side ladders on.
The beams are 3m x 300 x 95 PFC, and each flange is about 15mm thick, so I have been concerned about how to drill them.
I raised the beams off the ground and levelled them as in the post above, then I put the drill onto a trolley and moved it under the beam to drill each hole. I found I had to chock the trolley and also brace between the drill base and underside of the beam, otherwise the drill would just ride up when I lowered the drill bit.

I worked down one side, bolting (on the drilled side) and clamping (the unddrilled side) each cross member, then worked down the other side, moving one cross member aside at a time to allow the drill access to the next hole to be drilled, and then bolting both sides of the cross members as the drill passed by.
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  #54  
Old Mon 18 October 2010, 03:17
AuS MaDDoG
Just call me: Tony #71
 
Brisbane
Australia
Looking Good!!

Thread should be moved to Construction Started but not cutting!!

Cheers
Tony.
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  #55  
Old Tue 19 October 2010, 19:04
Red_boards
Just call me: Red #91
 
Melbourne
Australia
Tony,
I don't mind. The build progresses regardless.
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  #56  
Old Tue 19 October 2010, 19:18
Red_boards
Just call me: Red #91
 
Melbourne
Australia
2 questions: Locater tabs and Protection for MDF support board

Fixed the support board under the cross members.
Laid the board on the floor, skateboard under one end. Rolled it under the inverted table.
Lifted the board, squared it and clamped it in place.
Having holes drilled through both flanges of the cross members (thanks, Ross) made it really easy to use a hand drill to pop holes down through the board.
Slide around underneath and countersink. Lots of sawdust in my hair.
Bolt up and it's secured. Long arms help to hold the centre bolts under the board and get the nut on at the top!

Bugger! The beams are 0.5mm out of alignment at one end.

Now on to building the longitudinal leg assembly (seemed easier to have the cross supports in place so I could be sure of missing them with the legs and flanges for bolting legs on).

Two questions:
1. Since I have to dissamble in order to paint, what about welding tabs onto the cross members at the beam to locate the beams at correct width for accurate reassembly? Or will the 9mm bolt holes with 8mm bolts do this accurately enough?

2. What do I coat the MDF in to protect it?
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  #57  
Old Wed 20 October 2010, 05:58
Surfcnc
Just call me: Ross #74
 
Queensland
Australia
Hi Red

For an undercoat try - Blitz Total, it is a very tough exterior water based acrylic.
Good for virtually anything (including MDF) and is the best primer sealer undercoat I have come across.
Impact resistance, film strength and bond to the substrate is excellent.

It is distributed through Amazing Paint Discounts here in Australia.
They are solver paints stockists so Solver may make an equivalent.
Topcoat I would use an enamel paint of your choice and it is ok to mix the acrylic base with the enamel top coat in case you were wondering.
Clean all dust from the raw MDF board before painting with a damp rag and work the paint in with a roller to get the best bond.

The board will warp when it is painted on the sides and one face but will pull flat once mounted to the cross bearers.
I would not paint the other side as a further sacrificial spoil board will be glued to that remaining clean face later.

I used some Kinetix Surfboard Epoxy to fill over the cuphead bolts.
An ever so slight overfill will relax back down to level once the MDF takes a bit up.
Also used a bit of white pigment as a depth warning in case the cutter ever got that deep.

Regards
Ross
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  #58  
Old Wed 27 October 2010, 22:06
Red_boards
Just call me: Red #91
 
Melbourne
Australia
Thanks for the heads up on Blitz Total. And the smart idea for pigment. I'll file that one for when I get to the painting and filling stage. (Started grinding some welds to neaten them up. The bits might be welded together, but all that extra welding sure takes some grinding down! Time to consider a "big" grinder). A few weeks before I get to that stage, though.
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  #59  
Old Wed 27 October 2010, 22:36
Red_boards
Just call me: Red #91
 
Melbourne
Australia
Leg sub assemblies done

Well the bits that keep the beams off the ground and roughly parallel are almost done. I built the leg sub-assembly on top of the beams (i.e. upside down). This worked because I could not move the beams around and I did not want to work under them suspended 3' from the ground. Once I had the beams level and parallel they formed a nice base for getting the leg sub assemblies done.

I had the short (y-axis) subassemblies done, so could clamp them in place on the beams and use the lower longitudinal support to get the spacing right and the two vertical bearers to get the longitudinal support at the right distance from the beam. The pic below shows all these bits clamped together ready for tack welding. TIP: you can never have too many clamps! I always seemed shy one or two..


Once the longitudinal ladders were tack welded I unbolted the legs from the Y-axis ladders and took the frame to ground level where I could do some horizontal welding (which is about where my "skill" level stops!


Once the "easy" 90 degree bits were done I could cut the angle braces and weld them in place. Cutting the angles proved tricky because thher were greater than the clamps on my cut-off saw allowed. A lot of messing with G-clamps and one broken blade (darn!) when the piece wasn't clamped tight enough and shifted.

Eventually I got the angles fitted and welded and could bolt the longitudinal sub assemblies back to the y-axis ones. Observant people will see that the legs are off centre in the picture. This is because I have them clamped to a cross support so the entire leg sub assembly does not slip off the beam and hurt someone important (mainly me!).


I could now square up the leg sub assembly and weld it in place and be done, but I'm going to weld plates to it and drill them and the beam so that I can bolt the legs to the table. So the table will break down into 6 parts - two y-sub assemblies for legs (light), two longitudinal sub assemblies (heavier), two beams (heavy).

Last edited by Red_boards; Wed 27 October 2010 at 22:37.. Reason: insert missing bracket to fix picture link
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  #60  
Old Wed 27 October 2010, 23:03
AuS MaDDoG
Just call me: Tony #71
 
Brisbane
Australia
Wow !!

The size of those beams make the rest of the table look so small
Good work and keep the photos coming.

Cheers
Tony.
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