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  #211  
Old Thu 10 March 2011, 07:09
myousry
Just call me: myousry
 
alexandria
Egypt
Quote:
Originally Posted by IN-WondeR View Post
Hi Myusry

It's looking good.

I'm a bit been on finding out why you are using 2 square tubes to make the gantry. I don't know how large those tubes are, but it seems like they are quite thin. I would imagine it would bend a little over large lengths.
other than that I believe it looks very good.

The router mount should be with the large backplate instead of the smaller one. I have made only the mounts for the spindle, and not the backplate, My backplate is the z axis it self. I have thought of changing that so I can mount and dismount the whole router mount from the front instead of the back.

Kim
they are 4mm thick and the tube are 2 meter length each should i replace them . what is the right thickness for these 2 meter square tube so as not to get bend will working
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  #212  
Old Thu 10 March 2011, 09:16
Allegheny
Just call me: Brian
 
Massachusetts
United States of America
The other concern I would have with a multi-part gantry - as opposed to a single large tube on which to mount the z-axis - is the difficulty in keeping everything in alignment. As configured, there are six pieces of tubing - the 2 main cross members, the two spacers holding them apart, and the two uprights holding that assembly to the x-axis carriages. Getting all those pairs of parts to the exact same size, holding them in position while welding, and then trying to later adjust for all the warping and twisting that WILL occur would be nearly impossible. I suppose you could do it with a mongo surface grinder, but going with the single tube is so much easier.

Just my $0.03 (have to account for inflation)

Brian
Taxachusetts
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  #213  
Old Thu 10 March 2011, 12:56
myousry
Just call me: myousry
 
alexandria
Egypt
thanks brian i will try to multi-part gantry because of the MBA-15C Nema 23 motor mount
i bought from http://www.slidesandballscrews.com/m....html?cPath=74 and and the MGD 20 mm ball nut housing from http://www.slidesandballscrews.com/b....html?cPath=72 . so i have to have a clear path for the moving ballnut housing , using a single tube would be impossible. unless you want me to make a straight clear groove all over the single tube to clear the path for ballnut housing , but will this weaken it as it has taken a letter C shape ?
myousry
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File Type: jpg mm2.jpg (41.2 KB, 1334 views)
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  #214  
Old Thu 10 March 2011, 13:03
Allegheny
Just call me: Brian
 
Massachusetts
United States of America
Hi myousry,

I see what you need to do. But there's more then one way to "skin a cat" as we say in the states.

How about spacing the ball screw mounts further from the gantry by putting some 1.0 cm (or 2.0 cm or whatever it takes) thick spacers between their bases and the face of the gantry so the moving portion will clear the face of the gantry? Seems to me that would be much simpler and accomplish the same goal.

Brian
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  #215  
Old Thu 10 March 2011, 13:20
myousry
Just call me: myousry
 
alexandria
Egypt
Hi Brian
seems to me a good solution. the gantry length will be 2 meter .what's your suggestion about the thickness of the single tube?
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  #216  
Old Thu 10 March 2011, 15:07
Allegheny
Just call me: Brian
 
Massachusetts
United States of America
Hi myousry,

While I wouldn't consider myself "metrically" challenged, I'm not all that familiar with common metric stock sizes. Looking at the gantry in post #197, I'd estimate it at 4x8" tubing, maybe even 5x10" or 12" (so 100 to 125mm wide x 200-300mm tall). I would think you'd want it to be at least 3mm thick, if not 4 to provide adequate strength but not to be so heavy as to retard movement by overburdening the x-axis steppers.

Hopefully, Kim will chime in and provide you with the dimensions of the tubing he used ....

Brian
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  #217  
Old Thu 10 March 2011, 16:33
IN-WondeR
Just call me: Kim
 
Randers
Denmark
The tube I used is 140x260mm and 6mm thick. So it's quite a heavy and strong one I have.
It would translate to around 5.5" x 10.5" and 1/4" thick. it's 1800mm long, or around 6feet. the tube alone weighs in at around 120 pounds. The whole gantry is around 230 punds. including the uptrights z axis and motors and so.. Perhaps a bit more.
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  #218  
Old Thu 10 March 2011, 22:31
KenC
Just call me: Ken
 
Klang
Malaysia
sounds heavy...
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  #219  
Old Fri 11 March 2011, 00:35
IN-WondeR
Just call me: Kim
 
Randers
Denmark
Hi Ken..

Yeah it's heavy. After my breakin in the garage last year, I decided that it should be more difficuelt to remove my gantry this time, so I opted for some weight instead of totally redesigning my table also... For now, it's going to take atleast an hour or more to remove everything this time... Hopefully it will not be something I need to worry about, but one never knows. This time it's also insured...
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  #220  
Old Fri 11 March 2011, 02:08
myousry
Just call me: myousry
 
alexandria
Egypt
thank you guys for your help i will take your consideration all your notes. i am going to search for the appropriate single tube with 1/4" thick as minimum. what's your minimum stepper motor oz on each side you have each side to move this heavy gantry with everything on it
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  #221  
Old Fri 11 March 2011, 03:08
KenC
Just call me: Ken
 
Klang
Malaysia
Hi Kim,
It is a real surprise your unfortunate break-in incident has effect on your machine design!
Having more mass on the gantry surely will damp some vibration when doing aggressive cuts. Really looking forward to see how the motors will live up with the extra weight, which I have good faith that they will perform adequately, especially with the belt reduction..
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  #222  
Old Fri 11 March 2011, 04:25
IN-WondeR
Just call me: Kim
 
Randers
Denmark
The motors are rated 4.5Nm pr side. Running a 3.33:1 belt reduction, giving me almost 15Nm pr side of the gantry. The power is more than enough, my weak link at this time must be the chains. As said I have very little chatter when makin 90 degree turns, but it's very little, and hardly noticable. I'm trying to see if I can make a slight pause when chaning direction from x to y, the other way around is no problem. It's only when I change direction from x to y. For now I have not gotten CV to work as it should though.
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  #223  
Old Mon 14 March 2011, 19:59
shaper
Just call me: Jed
 
Perth, WA
Australia
Hi Myoursy

While the thickness is important from a bending perspective it's not he end of the story and infact the profile is atleast as important as the thickness. If you want to avoid deflection over the same span you don't necessarily need to go thicker but the profile Kim is suggesting will certainly will be stiff in almost any thickness over the span you are considering. I'm not sure what profile the SHS you have in the drawing is but the same effect could be reached by simply modifying your profile choice. This does not consider the vibration effects of the additional weight.

I do agree with Brian how ever that managing warpage in this kind of design is going to be difficult, but IMO this is relevant in the MM design also (else Gerald wouldn't have given us very good clear instructions on how the gantry should be welded up) and the same principles can be used in a design such as yours and the remainder could be shimmed out as it is in the MM design.

I'm planning a build similar in concept to you as I'm having trouble sourcing a 250mmx150mmx4mm beam similar to Kim's, hence I have been giving this a deal of thought also.
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  #224  
Old Mon 21 March 2011, 01:26
IN-WondeR
Just call me: Kim
 
Randers
Denmark
Well, a few flaws have surfaced in my design, and sadly, the bearing support idea I made for the pinion/pulley axle on the X axis, cannot take the strain, mostly because of the small area taking all those axial and thrust forces the 130kg gantry gives. So I will be making a set of gearboxes for the x axis, so I can get more support for the bearings over a larger area, rather than only 16mm. But, it cuts, and actually quite ok. Next up is my dust collection... :-D Enjoy
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File Type: jpg DSC01854(1).jpg (133.1 KB, 1146 views)
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  #225  
Old Mon 21 March 2011, 02:21
KenC
Just call me: Ken
 
Klang
Malaysia
Very good finishing! Especially the relief carving.
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  #226  
Old Mon 21 March 2011, 06:22
myousry
Just call me: myousry
 
alexandria
Egypt
hi kim i intend to add these gearboxes to my design
http://www.slidesandballscrews.com/g...y-c-66_67.html
i hope they help you. what do you think about their backlash ? do you know anyone else selling gearboxes with the least backlashes ? thanks for help
regarding the single tube design i found a metal wholesaler that sells these kind of these tubes it will 30cmx17cmx6mm thickness with a length 220cm. is it okay to go for it ? or there a fear from the bending issue ?
thanks a lot for your help
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  #227  
Old Mon 21 March 2011, 07:00
Allegheny
Just call me: Brian
 
Massachusetts
United States of America
Ouch - that is a huge tube! The only bending I'd be worried about would be the support table! Would sure make for good dampening though. With such a heavy tube, I would think you'd need some serious gear/belt reduction on the x-axis motors.

Brian
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  #228  
Old Mon 21 March 2011, 10:56
IN-WondeR
Just call me: Kim
 
Randers
Denmark
Thank you Ken, I'm also quite happy with the finish. Only bad thing is the time it took to make the relief carving. Almost 1.5 hours, because of the chains I cannot carve like that with more than 1000mm/min, I would like to go up to atleast double that speed. The big sign I made, is made of Larch, and planed with the CNC it self. It turned out great.

Myousry
Those gearboxes look to me not to have zero backlash, they will be quite expensive when you add the low backlash option to the, that's another 50£ a piece. I would go for a belt reduction instead, that would probably do better than any gearbox you can find. I will be making a belt reduction for mine so I can have it pivot, and I can add tension to the rack&pinion setup.

Allegheny
Yes, it's a huge tube, but no bending issues on such a tube, but you need some serious power if you go that big, but you will not have any bending problems. Just make sure you make your basetable very very sturdy...
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  #229  
Old Sun 27 March 2011, 18:10
PEU
Just call me: Pablo
 
Buenos Aires
Argentina
Saw this router and inmediatelly I remembered your design:

First thing I noticed is that the guides and the ballscrews did not use any protection for dust, and if you machined MDF you know that powder has the ability to reach unthinked places! I would cover them with something even with a vacuum system in place.

The gantry moves via a hiwin ballscrew (35 or 40mm diameter by the eye) on one side, uses the same motor as the other axis.

The gantry rides on 30mm hiwin rails three per side, gantry and Z are 20mm rails








The base is filled with concrete or epoxy mix for more rigidity.

Overall it looks like a solid machine, my only concern is dust on the linear guides and ballscrews.


Pablo
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  #230  
Old Mon 28 March 2011, 00:29
IN-WondeR
Just call me: Kim
 
Randers
Denmark
That's actually a Nice machine you found there... And yes, MDF dust is very persistant and is the worst thing when cutting on a CNC, but with a good dust management system, then it should not be that big a problem. Right now my Cyclone build haven't been finished yet, so I'm cutting very little, but when I get it done, then I should be able to take all dust away from the machine when cutting.

But again, very nice little machine you found there, but the robot is a bit malplaced. :-D
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  #231  
Old Mon 28 March 2011, 05:51
Allegheny
Just call me: Brian
 
Massachusetts
United States of America
I like the built-in bottle/cup holder !

Brian
Taxachusetts
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  #232  
Old Mon 28 March 2011, 09:01
PEU
Just call me: Pablo
 
Buenos Aires
Argentina
Quote:
Originally Posted by IN-WondeR View Post
That's actually a Nice machine you found there... And yes, MDF dust is very persistant and is the worst thing when cutting on a CNC, but with a good dust management system, then it should not be that big a problem. Right now my Cyclone build haven't been finished yet, so I'm cutting very little, but when I get it done, then I should be able to take all dust away from the machine when cutting.

But again, very nice little machine you found there, but the robot is a bit malplaced. :-D
Their booth is small for the amount of machines, so they put the robot over the table, and it loads demo boards that are held in place by a suction cup
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  #233  
Old Fri 29 July 2011, 10:20
IN-WondeR
Just call me: Kim
 
Randers
Denmark
Just added new gearboxes for my x axis, and the y axis have now been added a ballscrew. (picture missing)
Just wanted to show of these beefy gearboxes I made.
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File Type: jpg IMAG0080(1).jpg (85.9 KB, 827 views)
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  #234  
Old Sun 31 July 2011, 05:52
IN-WondeR
Just call me: Kim
 
Randers
Denmark
Workstation setup on the machine instead of a standalone table..
just finished it today.
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File Type: jpg IMAG0081(1).jpg (287.5 KB, 791 views)
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  #235  
Old Thu 04 August 2011, 20:23
javeria
Just call me: Irfan #33
 
Bangalore
India
Hi Kim - where have you installed the Rack, - i assumed that you used the gearbox for the chain, then just read back about the rack- somme more pics
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  #236  
Old Fri 05 August 2011, 05:44
IN-WondeR
Just call me: Kim
 
Randers
Denmark
In post #233 you can just see the rack under the blue lip next to the gearbox, there the rack is mounted upside down.
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  #237  
Old Mon 29 August 2011, 14:30
IN-WondeR
Just call me: Kim
 
Randers
Denmark
Well, I finally got my gearboxes and my ballscrew mounted and all the motors hookes up again. Damn it's great to see the big old blue beast move again.
Finally I can go on and get things started, get the machine properly tuned and tested before any kind of production starts.

Enjoy some of the final pictures I will post on this forum. A few parts is still not finished, like the home switches, but they will be finished soon enough.
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File Type: jpg IMAG0089(1).jpg (267.4 KB, 611 views)
File Type: jpg IMAG0091(1).jpg (272.0 KB, 614 views)
File Type: jpg IMAG0090(1).jpg (292.6 KB, 615 views)
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  #238  
Old Mon 29 August 2011, 16:37
danilom
Just call me: Danilo #64
 
Novi Sad
Serbia
It really looks MASSIVE! Well done
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  #239  
Old Mon 29 August 2011, 19:27
PEU
Just call me: Pablo
 
Buenos Aires
Argentina
It really looks great Kim, congratulations, please share more photos! I could really fit a machine like that one at my office
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  #240  
Old Tue 30 August 2011, 08:33
IN-WondeR
Just call me: Kim
 
Randers
Denmark
Danilom

It is massive, but still it only weighs around 700kg in total. The main framework weighs around 300kg, the tabletop weighs a massive 200 kg, that's the floating part and the 40mm MDF. The gantry with all it's fixings weighs almost 200kg, so all in all around 700kg, but it's the way it's put together that makes it so sturdy as it is, there's absolutely no rock and roll in the machine when it moves, it's steady as a rock.
I made it as a standalone machine with no external parts on it, and it has so far paid of, the entire machine with cables, drives, motors and so on, can be moved in one piece, no need for anything to be unplugged first. Only thing that will be coming from outside the machine is an extension cord, and an airhose when I get that added also.
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