Ridgid mill/router

[louieatienza]

That's a very good looking machine, Louie. Now that I see your Z and how small the bearing blocks are, I know why you were recommending 4 trucks on the other thread! In my head I was picturing something much bigger - there was no scale in the picture on the other thread.

How is the "Y" (Z for henry) span attached to the uprights? My eye is asking me to add a couple more of those gussets to your gantry, both at the top and at the bottom, perhaps only at the bottom if there's additional fasteners holding the Y span to the uprights in addition to the gussets.

Thanks Andy! These small rails actually have really good load ratings for their size. The difference in height between these and regular 20 series rail is huge. When I do version 2 of the carriage assembly I hope to pull the components in even more.

There are atually 8 bolts per gusset, four a side. Because of the overall weight, the easiest way for me was to install the uprights first, then slide the gantry beam (sans carriage) through the t-nuts. This was harder than I thought, and I had left the Allen key at the tablesaw. I finger-tightened the two outer bolts and left the gantry cantilevered over the outside of the table about 24" and i saw no visible deflection on the lower plate, upright, or gusset! I do plan to add connectors to the outside of the uprights, but the machine would run fine without them.

As for the lower plates, I do have holes drilled already for gussets. Since the spindle center goes PAST the table on each side, I needed to make sure the gusset cleared my largest bit, so I could make the gusset as large as possible. Also it would be my first job on the machine!

As it sits, this thing is getting pretty damn heavy! I think this table is not going to cut it, so I plan on making a new table out of framing lumber and plywood. I want to make it large enough to also allow for some workspace.

[Drools]

Yes the weight adds up fast. I have to replace the casters I used on my table as the rubber is splitting from the load... oops I guess the load rating is not quite what they say it is for these castors.
I'm looking forward to see your machine cutting some aluminum.

[FannBlade]

I'm looking forward to see your machine cutting some aluminum.

Me too.

Keep up the great work Louie

[louieatienza]

Me too.

Keep up the great work Louie

Thanks, me too! Ran into a little problem. I forgot that the shafts on my steppers are 8mm (5/16") and I ordered 1/4" bore pulleys. Not sure if I want to bother boring them out... would be easier to just get new ones.

[zool]

Very artful industrial device.

[louieatienza]

Very artful industrial device.

Thanks zool... good to see you here again!

[louieatienza]

I am now waiting on new timing belts and pulleys. I spoke with an engineer at Misumi, and according to their calculations, 25mm S5M belt would be better suited to my application. The XL belts and pulleys I planned to use was too small (3/8") and the tooth pattern was not the best for higher loads and backlash. I'll repurpose them for my current machine.

I also plan to decrease the drive ratio a bit from the 4:1 I originally planned. This is because the engineer at Misumi showed the motor pulley wouldn't run properly at the speed I need with the smaller size. So I'm going to have to go to 24 or 25 teeth on the motor. I'll still have a final drive ratio around 2.25:1, which should still be plenty to move this machine around. Even with the initial 'sticktion' I can still push each axis with one finger...

[RomanLini]

Louie, why did he say 3/8" belts are too small? 25mm belts are not normally needed unless you are driving a tractor or something.

You're still talking about the belts needed to couple the stepper motors to the leadscrews right? I'm confused.

[louieatienza]

Louie, why did he say 3/8" belts are too small? 25mm belts are not normally needed unless you are driving a tractor or something.

You're still talking about the belts needed to couple the stepper motors to the leadscrews right? I'm confused.

I thought the same, but I guess with my estimated force needed to push each axis, the power of the steppers, weight of the Z, and speed of the stepper motors, the engineer felt that this was the right choice. Even have the calculations sent to me on a spreadsheet.

Then again, with HSR30s for the X, why stop there?!

[RomanLini]

Thanks for the info.

Generally the belt pull force will be less than the stepper torque at the stepper pulley radius, and if it exceeds that the stepper will jump steps anyway. For most motors (<400 oz-in) and pulley radii (0.5"?) that force will be below 400 / 0.5 or 800 oz, about 45 pounds pull force on the belt.

I suppose with monster steppers that force can get up there, but it still took me by surprise when he suggested 25mm belt size for the reduction belts.

[harryn]

The 25mm sounds about right actually. You can use smaller belts if you just want to transmit power in one direction, but if you want to transmit motion and power, the instantaneous forces rise quickly.

I did the calculations on a fully belt driven system that I was attempting, and one axis was calling for 100mm wide belt. It is a combination of elongation and tooth strength that drives the decision, not really belt strength.

[louieatienza]

When I get the chance I'll post the spreadsheet sent to me on the analysis of my drive system. Having the stronger tooth profile and smoother motion from the larger pulley made sense to me. The engineer did say that rubber belt would be fine.