Re: GME's New 80/20 CNC Build - My Design
Quote:
Originally Posted by
davida1234
Well, then go ahead and try the gussets, maybe it is enough.
We'll see. I'm hoping the gussets will work, but I'm not holding my breath. The basic design is proven to work - at least using steel for a steel machine. Whether, or to what extent, it translates to my machine is an open question. I'm going to see if I can cut the gussets on the CNC. I could drill the holes on my mill, but I would still have to saw the basic shape. I only have a small bandsaw, so I'd have to do it with my table saw and miter slider equipped with non-ferrous blades. I sometimes do it, but try to avoid it. The CNC would sure be faster, but then, you already know that.
Any more thoughts about addressing the 5 IPM resonance issue on the Y axis? When I get a more time, I may remove the stepper drives and go through them again with everything removed. Otherwise, I don't know what more to do. Feels like taking two steps forward and one step back.
Gary
Re: GME's New 80/20 CNC Build - My Design
Try reducing the current to maybe 6 amps or so on the drives, and see if that helps? You could always try a different drive, like a Leadshine EM806 and see if it's smoother? I've heard that they are. Testing an Leadshine AM882 on a bench, I get super smooth rotation at even really slow speeds.
If you pull the motor, and run it on a table, does it still have resonance at the same speed?
I don't think it's a big deal, as it's unlikely you'll actually ever cut anything at 5ipm. But you'll have to see if it affects anything.
Re: GME's New 80/20 CNC Build - My Design
Gary I think cutting your plates on the machine is an excellent way to go and you can also drill. When my machine was almost done and before I had the spoil board I had a job come that had to be done. I just C Clamped a piece of MDF to the table cross braces and got it done.
In fact you could use a hunk of scrap plywood to do a prototype before your metal arrives.
My gussets, the triangle shape helps add strength to the corner as well as holding the metal together. Mine is 8x5 inches on the sides and about 6 inches from the corner to the center of the triangle.
Like Gerry I don't think your stepper motor noise is a deal breaker.
Re: GME's New 80/20 CNC Build - My Design
Quote:
Originally Posted by
GME
Otherwise, I don't know what more to do.
A far fetched idea, probably won't help but ...... Loosen the stepper on one drive and skip the belt 7 tooth and reassemble.
Re: GME's New 80/20 CNC Build - My Design
Quote:
Originally Posted by
ger21
it's unlikely you'll actually ever cut anything at 5ipm
Every time you cut a circle, one axis slows down from full feed to zero and goes back up. Passes over 5 ipm four times for a full circle.
Re: GME's New 80/20 CNC Build - My Design
Yeah, but it's very brief, and it's accelerating and decelerating past 5ipm, not staying at 5ipm.
Re: GME's New 80/20 CNC Build - My Design
Quote:
Originally Posted by
davida1234
A far fetched idea, probably won't help but ...... Loosen the stepper on one drive and skip the belt 7 tooth and reassemble.
Everytime the machine Homes and its re-zeroed you will need to do that all over. He has Y and a Slave like mine.
Re: GME's New 80/20 CNC Build - My Design
Quote:
Originally Posted by
ger21
Try reducing the current to maybe 6 amps or so on the drives, and see if that helps? You could always try a different drive, like a Leadshine EM806 and see if it's smoother? I've heard that they are. Testing an Leadshine AM882 on a bench, I get super smooth rotation at even really slow speeds.
If you pull the motor, and run it on a table, does it still have resonance at the same speed?
I don't think it's a big deal, as it's unlikely you'll actually ever cut anything at 5ipm. But you'll have to see if it affects anything.
Great ideas, Gerry. Thank you.
As you might guess, it's hard to get excited about the prospect of spending about $300 (with shipping & tax) for 2 new drives, or double that, if I were to replace all 4. Nevertheless, I have to admit I like the specs and descriptions on the EM806s. It's out there as a viable option, and one I would exercise, but pretty much as a last resort. It's good to hear you have some experience with them. Unfortunately, to use them means a complete remake of my control box, or having to add an auxiliary box.
I took an unconventional approach when building my control box. Avid CNC uses the removable plate on their boxes to mount the connectors. I removed mine, rotate the box so the opening was on top, and in place of the plate, I installed a huge heat sink with the fins open to ambient air. I screwed the Stepper drives to the underside of the heat sink. It's a design I used when I built an electric brewery. It works great.
My first step will be to try the current set resistors to reduce current and test. If the problem persists I'll pull the motors and see that makes a difference. If it doesn't, I can rule out other mechanical causes, like the R&P drive. On the flip side, if the stepper is fine on the bench, the problem probably resides in the drive line, like in the stepper drives.
As you observe, Gerry, this may not turn out to be a big deal. Only doing actual cutting will tell me one way or the other. Still, it makes sense to me to try the the low cost/cost free stuff before pulling the trigger on larger purchases.
Quote:
Originally Posted by
davida1234
A far fetched idea, probably won't help but ...... Loosen the stepper on one drive and skip the belt 7 tooth and reassemble.
Thank you, David. Yup, sounds far fetched, but I'm not taking anything for granted. I don't know what I don't know. If I get to the point of removing steppers, I'll be sure to give it a try.
Thanks again, guys.
Gary.
Re: GME's New 80/20 CNC Build - My Design
Quote:
Originally Posted by
wmgeorge
Gary I think cutting your plates on the machine is an excellent way to go and you can also drill. When my machine was almost done and before I had the spoil board I had a job come that had to be done. I just C Clamped a piece of MDF to the table cross braces and got it done.
In fact you could use a hunk of scrap plywood to do a prototype before your metal arrives.
My gussets, the triangle shape helps add strength to the corner as well as holding the metal together. Mine is 8x5 inches on the sides and about 6 inches from the corner to the center of the triangle.
Like Gerry I don't think your stepper motor noise is a deal breaker.
Thank you, Bill. Yeah, I did similar on my first machine before I got the spoilboard on. Worked okay, but far less convenient than with the spoilboard. I plan to leave the temporary side braces in place for whatever additional support they provide. Can't hurt.
Agree about the prototyping in scrap ply. Work out any kinks before going with the expensive stuff. It will have to wait until Monday, though. I'm at the beach with my wife this weekend. We have a place out here. We come most every weekend the year around. The weather at the Washington coast is pretty moderate. Stays cool in the summer (it's 67 degrees right now). In the winter, the highs are in upper 40s to low 50s. Maybe one minor show per season that melts off in one or two day. Rains a lot in the winter, though.
Thanks for the dimensions on your gussets. I make them slightly smaller in my design, but have enough material to make them 5" x 8". An easy modification. I draw one, and use "array" to copy as many as I need and where I want them. The piece of stock I ordered was large enough to accommodate the 1/2" increase in length and width.
We'll see about the resonance issue. I hope it turns out to be a tempest in a teapot.
Gary
Re: GME's New 80/20 CNC Build - My Design
Hey Gary have a great time at the beach and forget this stuff for a while. Its been way to hot and just now I made a run to Culver's for take out supper. Left home looked back and huge storm clouds to the NW. Got out the Iphone, nope weather is fine no warnings. Needless to say on the way home I was hit with 70 mph winds, heavy rain and some hail. Got home streets flooded, trees down and gee now the weather shows heavy Thunderstorms.... this over a 20-30 minute time frame, 1.4 inches of rain and lucky no hail damage to my truck that I can see anyway.
Re: GME's New 80/20 CNC Build - My Design
Hi Gary - A brace is a secondary structure, it preserves the shape of the primary structure and therefore can be quite lightweight. Before you commit to doing the modification simply G clamp whatever you have handy across the legs and see if it works. If it works then do it more formally if it does not work then you can look elsewhere for a solution. The test could use a sheet of material or a beam section same effect. Peter
Re: GME's New 80/20 CNC Build - My Design
Quote:
Originally Posted by
peteeng
Hi Gary - A brace is a secondary structure, it preserves the shape of the primary structure and therefore can be quite lightweight. Before you commit to doing the modification simply G clamp whatever you have handy across the legs and see if it works. If it works then do it more formally if it does not work then you can look elsewhere for a solution. The test could use a sheet of material or a beam section same effect. Peter
Thank you, Peter. See Post #231. There are photos. Been there, done that, except I bolted some aluminum angle to the legs with two bolts per end. Then, I bolted the angle to the underside of a 1.5" X 3" 8020 extrusion with another two bolts per end. The arrangement I used did what I wanted it to. That's why I moved on to gussets. I figure a much more rigid connection would be no worse than my test, but almost certainly better.
I've never heard what I know as C clamps referred to as G clamps. A quick search revealed they are the same thing. I was concerned that using a single clamp at each end might create pivot points and not give a true picture. I could have used 2 clamps at each end, but that gets kind of crowded. I was also concerned about damaging the extrusions. Too loose, and you get movement. Too tight, which is easy to do with C or G clamps. The figure the way I did it avoided any risk and provided a rigid connection. It was also pretty easy, since the angle located the extrusion where I wanted it, and supported it as well. Easier than trying to position a 68" long piece of extrusion while juggling a bunch of clamps - at least for me.
Too bad the 4 x 144" .080" sheets of aluminum I have squirreled are too thin for the task. I've used it for various things over the years, but it thinness has been a factor limiting its utility. I cut some square tubing into quarters, forming 4 angle pieces. They were under 1/8" thick. I cut some of my .080 stuff into strips and fastened it to the homemade angle. I used it for trays for my cable chains. Worked great. With the angle backing a long edge, it proved plenty stiff for cable chains full of cable and water lines for my spindle. Not much work, and cheaper than the stamped steel ones. Also, I made it to the length I needed and wasn't bound by stock size.
Thank again for checking in Peter. More to follow . . . .
Gary