Upgrading a PRT Alpha

[fleinbach]

Brian,

Yes, I will good or bad. It could be a little while as I have been really tied up this week replacing 2 second floor bedrooms a tree fell on.

Also while I was in the upgrade mode on the Shopbot I decided it was time to change my monitor. I was using one of my old 20" KDS tube monitors which took up a lot of space but while shopping at the local flea markets noticed I could pick up a small LCD for around $50.00. But while searching I found a neat computer with a built in LCD screen. I never saw one of these before. It's compact like a laptop but doesn’t fold up. I thought why not replace both the computer and screen and really gain space.

Well the one I found didn't have a power supply so I came home and searched on eBay for one. I found many available made by Gateway. They are called Gateway profiles and I saw several models from 933MZ up to 2.8GH. The one I got was a 1.3GH for $107.00. I thought I'd point this out for anyone interested in a really neat compact solution for a computer and LCD screen to run the bot.

BTW. I did a speed test with the software Brady pointed out a few days ago. My old 800MZ computer was averaging 70.4 while this new one is registering 89.6

[beacon14]

I recently completed the 7.2/1 geared motor upgrade, and here is my report:

First the glitches: While the mechanics of swapping the motors are pretty basic, it required what I'm sure was divine intervention to get the washer and nut on the Y motor bolt without removing the Z axis for access. My Z axis is mounted as close to the Y motor as possible,and there was almost no way to get a wrench let alone my fingers into the spot just inside one of the Y carriage wheels where the threaded end of the bolt sticks through. I ended up taping the washer to a thin scrap of wood to hold it over the hole while pushing the bolt through from the outside, then just managed to get the nut on and, while holding my breath and saying a little prayer, slipped a thin 14mm wrench from my Jet planer between the rail of the X carriage and the end of the Y carriage and was able to get the threads engaged. Until that moment I was sure I was going to have to remove the Z axis.

I also ran into a problem with a cable that had been damaged in shipping - the cables are shipped attached to the motors with heavy duty heat shrink over the connectors. Apparently the motor flange had impacted the cable when the package was dropped at some point and it was enough to short two of the conductors to the shielding. I only found this out after hooking everything up and trying the motors while disengaged from the rack - there was a horrible grinding sound that I was sure was my gear box destroying itself. In short (no pun intended, and let me tell you I was not smiling at the time) I lost about an hour and a half diagnosing the problem, then replacing the new cable with one of my old cables all the way back to the control box.

I also wish our friends at ShopBot had taken advantage of Frank's efforts and put a copy of his instructions in the box - that would have saved me another half an hour on the forum looking for the unit values before I found this thread.

OK, enough venting. In the end the motors are replaced (and my wiring is completely re-routed, pics to follow), and it was worth it. Right off the bat the motors sound much smoother and quieter - more like a dentist's drill or other precision instrument than the meat grinder sound of the old motors. Speed tests confirm that the router is now by far the weakest link in the system whereas the motors and router were pretty evenly matched before. So only a small increase in speed so far - the spindle is on it's way - but dramatic improvements in cut quality and overall smoothness. Test cuts in MDF before and after the upgrade show a visible improvement (although I was getting pretty good cuts before.) Running a finger along the edge confirms the cut is much smoother. How much of this is from just replacing the pinions with new, larger ones and how much is from the motors I don't know and I guess it doesn't matter. I briefly considered putting the new gears on the old motors for a middle round of test cuts before taking the old motors off, but I had little enough time as it was and I had jobs waiting to test out the new motors.

Speaking of which, the results speak for themselves. After a weekend of cutting 35 sheets of melamine, I made these letters in beech, .28" deep, two passes with a 1/16" diameter straight bit. Two equal depth passes, no clean up pass. The same bit profiled the letters and cleared the area around them. The photo is exactly as they came off the machine except for vacuuming and blowing out the chips.


24463.jpg

[fleinbach]

David, Thanks for bringing my attention back to this topic to remind me I hadn’t given an update on the upgrade as yet.

At first I was a bit reluctant to post since after doing the upgrade I also made a change to my Y car before making any test cuts with the 7.2 upgrade. So I’m not sure how much this influenced the results. I wish I had taken the time to make some tests between changes but I had been contemplating the Y car change for over 2 years and once I was in upgrade mode I seemed to just keep going in that direction.

David’s comment kind of sums up my opinion as well.

“Test cuts in MDF before and after the upgrade show a visible improvement (although I was getting pretty good cuts before)”

In fact I agree with everything in David’s post pertaining to the way the Shopbot sounds. It is defiantly a smoother sounding machine.

As for the problem with getting a wrench on the Y motor bolt it was tight since I too have my spindle motor extremely close to that end of the Y car. But I was able to get the wrench in place without resorting to any extraordinary methods. But to do this I had to be standing in a precise position for my one hand to be able to position the wrench in front of the nut while my other hand pushed it against it. You defiantly need to be a contortionist to be able to do it.

[lto]

Our upgrade actually was fairly smooth, although some instructions may have saved calls to ShopBot. My 14 year old son accomplished most of it on his own.

Now for the really good part:
The machine with 3HP Colombo now performs to the quality level we envisioned prior to buying it nearly 3 years ago. We cut a lot of HDPE, cut quality has improved so much that we are seeing file time reductions of 30% along with greatly improved edge quality. We used to run a cleanup pass at .7 to reduce the chainsaw effect, now cleanup at nearly 3 times the speed produces a superior finish.

The motors do run hotter, but so far I see no reason for anyone to pass on this upgrade.

[brian_h]

I really appreciate the time you guys spent reporting on the upgrade. Thanks.

[gene]

So from what i gather the upgrade will be good if you are cutting mdf doors with a raised pannel look? Correct? this upgrade will be worth the investment ? Can someone post a photo of the inside cuts on mdf,? what does this do for the warranty on the new motors and cards? THANKS

[gene]

Hi ALl.
My bot has vexta Model ASM911AA motors dc 2.65v 2.1A
Are theese motors the 1to 1 motors or the 3.6 to 1 Motors?
Thanks

[Brady Watson]

They are direct drive or 1:1 motors. The PRT standard and PRS standard tools use 3.6:1 non-Alpha/non-feedback motors.

-B

[drodda]

Where do I find a price list of available upgrades for My PRT alpha online?

-D

[hespj]

"While we're on the subject of comm speed, you'll want to be sure to run the communication test application in the SB3 folder.".......Brady

What is this file called Brady, I don't seem to have anything that it could be.

John