Gantry Mechanical Design Calculations?

[JeremyFisher]

Obviously you could have used a combination of a few methods, but what I'm curious about is just how technical everyone got about it!

I'm in the design phase of my first router build, and I have read numerous times that newbies rarely get it right on their first build (in terms of rigidity and vibration). Fair enough.

To avoid disappointment with my machine, I've found that I've resorted to more and more precise design methods on each design iteration.

So now I'm wondering, how technical did everyone get in coming to their final design in their last or current build?

[toughtool]

Well, I'm not completely finished yet, but being a machine mechanic for 30 years (IBM service rep), an Amature Radio Advanced licensee, involved in photography since middle school (developing etc.), and having a 2,500 pound Bridgeport mill and two lathes certainly helps with understanding the physics of what is needed to make a reasonably sturdy CNC machine; and why a sturdy machine is necessity. However none of that tells you actually how to build one, so reading a lot of the posts here on CNCZone is I think an absolute necessity. From gleaning other peoples projects (and commits) you can see what not to do, and depending on finances, pick the best ideas of others' designs. Like Carverone's project, his project started out as a small 4X6 wood design but evolved completely into a different 4'X12' steel design, keeping the best ideas. For example, he changed the rails to better ground steel over the hot rolled ones. He deserted the wooden table frame for a steel table frame. He replaced the lead screws with rack and pinion drive. All of which cost him dearly I think. Would all of the first parts have worked? Yes, but he was going for a stronger machine. I loved his commit " ...Simply put, a monster sized Bridgeport milling machine looks the way it does because that's what it takes to mill steel effectively." I hope mine is strong enough to mill Aluminum and brass. If not, wood and plastic will be OK. I'm looking forward to making my next circuit board with this mill, rather than with a negative, photo resist and ferric chloride. After all I do cut aluminum and brass on my table saw and band saw.Joe

[diyengineer]

Looked at other machines, mimicked the best qualities of each. Everything started out on paper until i got the best things down. Then i went to solid works 2010. Started modeling, and posted a thread. Instead of using my mind alone, i tapped into the community here at cnczone. I would say close to 20 small design changes later outcome a quality 80/20 bolt together cnc machine. I also used stress programs lightly, but i usually build so overkill that it would be a waste of time to use them for the machines intended purpose.

If you have a quality idea run with it, but explore every option you can. That includes the hundreds of genius's located on this forum. =)

[Mogal]

I origionally purchased the PDJ Pilot Pro plans with a buddy.
He started on the base of the machine and I got the electronics going...
With life happening, the project got put on hold by both of us.
I ended up starting a JRO design, but life once again stopped that
I never did complete it... I got all the axis moving, but not powered.
I ended up selling the unit(But kept the electronics)

I got the PDJ base from my buddy, and started the build again... but with a little more knowledge.
I'm almost complete now, with all three axis moving but not powered yet.
I didn't follow through with the PDJ plans, I've taken the entire(the rest of the) design
from the projects posted here. Hopefully it will work out well.

No drafting/drawings no fancy 3D CADded drawings... just fliying by wire...
and all seems good so far... I'll start a build thread a little later on.

Long story short, I went through a couple revisions, took lots of time with design configurations, then finally got to work. I'm glad I did the wooden design first, as that
gave me the extra knowledge to run with the aluminum build.(I also didn't have my lathe and mill 2 years ago when I started)

And a harty thanks to all that helped unknowingly here on the zone! ;o)

[D.L]

Hi Jeremy, the status quo seems to be milled alloy plate sides for the gantry and a square hollow section base with either circular ball bushes acting as a structure as well as a guide, or the fussy way is the ball rail - it is a little sad to see them being bolted to twisted frames.
I know the ultimate is a space frame construction, light and rigid.
That requires careful planning and good welding, much like a kit plane, but the result would be amazing i have no doubts.

[diyengineer]

Originally Posted by D.L Hi Jeremy, the status quo seems to be milled alloy plate sides for the gantry and a square hollow section base with either circular ball bushes acting as a structure as well as a guide, or the fussy way is the ball rail - it is a little sad to see them being bolted to twisted frames. I know the ultimate is a space frame construction, light and rigid. That requires careful planning and good welding, much like a kit plane, but the result would be amazing i have no doubts.

If your referring to me:
The 80/20 machine I specifically designed to be a overkill bolt together construction kit that involved minimal milling and machinist tools. It was created with the intention of milling aluminum plate up to 1/4" but mostly .063" aluminum. For the price and simplicity as well as the rigidity it is a solid starter kit that could really be a workhorse. You could even assemble it in a few hours if you had everything laid out in front of you.

It is obviously not intended for someone who has the skill, knowledge, time, and money to build there machine from scratch out of tube, milled plates, etc. I would not call the custom machines better, but in a completely different class that involves many factors. (although i would love to say a sweet custom steel frame with granite epoxy is amazing, they are just two different classes and skill level sets).

Baby steps! Everyone has to start somewhere!

[srinimage]

HI..
I'm a new member. I need some clarification on Mach 3 software. I have developed a two axis rotary table using stepper motors for my CNC machines. I'm trying to synchronize my two axis system with the CNC Machine. Basically I want the stepper motors to run after getting a signal from CNC controller (i.e. I need to give 5v from CNC controller as a enable signal to Mach 3). Please let me know what are the changes I need to make in the Mach 3 software to accept 5v signal from CNC machines and then run a motor.

[JeremyFisher]

Thanks for all your inputs!

Originally Posted by diyengineer If you have a quality idea run with it, but explore every option you can. That includes the hundreds of genius's located on this forum. =)

I agree, hours of planning, calculating and designing is well and good, but other peoples experienced input is just as important, and that's exactly why I'm here. I haven't posted up my design yet because there are a few things I can still improve.
No point posting up incomplete work and getting suggestions for changes I was going to implement anyway.

Originally Posted by Mogal I'm glad I did the wooden design first, as that gave me the extra knowledge to run with the aluminum build.

I'm hoping that I can avoid a second build. Hopefully with the right design, I can iron out any problems and have a workable machine on the first iteration. My theory is similar to diyengineer's ie: overkill. If I want a machine rigid enough to cut wood, I'll design for it to cut aluminium, and it probably wont cut aluminium well, but it should cut wood no problems.

That's the plan anyway.

srinimage you'll get better help in the dedicated Mach Software forum:
Mach Software (ArtSoft software) - CNCzone.com

[Broken Balsa]

I wanted to build a unit that met two items. First I wanted to try rack and pinion. I am extreamly happy with the results of this. They develope a lot of power and run extreamly smooth. Also the use of them saves some funds for other things. Resolution is very good with them and at this time can achieve .001". We have tested the machine and feel this is accurate. If there is any bads to report on rack and pinion drive it would have to be it is some what difficult to keep the x axis rails clean. We are working on this problem. Right now we are using brushes to wipe the rails and while it works it is not the end solution.
The second objective was to have a router that could host a full sheet of plywood. This one can and by driving the x axis from both sides it is positive in movement with no veriations across the table. I used std. wt. 80/20 for construction and this while maybe a little more expensive was well worth it. Constructon of the frame was simple, fast and produced a very strong end product. To keep mistakes at a minimum I purchased a kit from CNCRouterParts.com in WA state. They were helpful and shipping was fast and accurate. The entire build was fun and it went together as planned with results as antisipated. The unit has Vetrics Aspire and Mach3 for systems. I am enjoying this machine and look forward to long service with little or no problems...BB