Hi from Seattle!

[buddyLumen]

Hi I am really considering this build. My concern is with assembling the table to acceptable tolerances with regard to rectilinearity/squareness so that everything runs smoothly with the gantry. Can anyone comment on this please?

Thanks
Buddy

[Fox]

You will manage, enough to be found on the forums regarding that.
The table does not need to be spot on actually, adjusting your rails will take care of that amongst others.

See this for more on squareness: http://www.mechmate.com/forums/showthread.php?t=231

[KenC]

That is the least concern. over 100 units were built, many of the builders has very poor building skill level.
All the comments & required know-how are well documented all over the forum. All u need to do is to sit down & keep reading.

[darren salyer]

Anyone who uses a word like rectilinearity should have no problems.
Welcome to the Forum!!

[pblackburn]

Even the big production cast machines are not parallel to start with and require skilled labor to make it absolute. If you can do basic trig and can use a level, string and some power tools it can be built with ease. Sure, the level of expertise you have will compliment your build but it will be built all the same. Perfection is not an act of practice but patience.

[Zouave]

Hi Buddy, and welcome! Take a little time with your setup, take the time to shim things properly (again, everything is available on the Forums) and you'll end up with a great machine. I just finished mine up, and while it was a long process, I think its an incredibly well-designed machine and I'm super happy with it.

[buddyLumen]

Thanks! Well after reading some more and finding a strong recommendation to build in a reverse order than I had been considering, that being: start with electronics and control mechanisms, then move to the gantry,...and finally finish with the table--whereas I had assumed starting with the table. I am wondering if others agree with this approach, and furthermore is there a necessity to do so because the finer points of the system (ie electronics and motion mechanics) might necessitate minor modifications to the larger structural items. If this is not the case then I would assume a simultaneous approach to the subsections of the build might not be a hasty approach...

[smreish]

Actually, the "kitchen table" project of electronics is the preferred method of the build.
It's the hardest (for some ) and most expensive, and you can effectively start executing cut files without the table to work on your cut file skills.

Good luck

[KenC]

Kitchen table project is a little project which get you to trial assemble your electronics &/or electrical works. don't have to be final assembly. You can do it as the 1st or last or any stage in between.

[dbinokc]

My process has been just to do whatever is needed to keep the build moving forward. So I may work on hardware some and then work on the electronics. Keep the build process flexible.

[buddyLumen]

Thanks for the replies. I think I am getting my head around the main points of this build. One thing that is eluding me so far, and yes I've been reading around, is: what is the actual drive mechanism of the machine in the x and y axis. I've seen some mention of Rack and Pinion, and some mention of Belt. Is there a preferred option here. I've put together a small desktop machine that was MDF and used small belts. It was okay as a starter project, but it seems to me a commercial quality machine should need something like the rack and pinion design, shouldn't it? I can see that the pics of the machines on the mechmate home page show racks mounted on the gantry and x-axis.

[smreish]

The mechanical drive for the machine is a 20 pitch rack and pinion arrangement.
The pinion can be driven 3 ways defined in the drawing package (which is confusing while reading posts)

- direct drive attached to the shaft of a standard stepper motor of proper size Nema 34
- built transmission (belt drive 3:1 or 4:1) with standard stepper motor Nema 34
- Oriental Motor geared stepper motor combination unit in either the 3.6 or 7.2 geared arrangement.

ALL of these solutions attached to the machine via laser cut swing plates which maintain the drive via rack and pinion.

[buddyLumen]

thank you smreish!

I will now go decode your transmission

[Zouave]

Sean beat me to it, but to help you visualize things further... When people on here refer to belt-drive, they are talking about a transmission that is between the motor and the rack attached to the rails. Here's an example of some different designs used for those:

http://www.mechmate.com/forums/showt...7&postcount=17

It effectively increases the number of steps it takes to move a given distance by 3x or 4x, or whatever ratio you build your belt drive to. The end result being greater torque, smoother cuts and increased precision. It still connects to a rack and pinion drive system at the end, though.