PRT Upgrades

[jdgrahamwaldorf]

Recently I have been doing more carvings and less panel cutting. I am looking at upgrading my bot to deal with the chatter caused by short, jerky movements. The three options I am looking at are linear rails, Shopbot's Z axis upgrade, and motor change. If anyone has made any of these changes and could relate the pros and cons I would be grateful. I am not looking at selling and buying a new machine because I like tinkering with my bot.

John

[tparr]

Here is a lot of excellant advice on how to smooth out your machine. It's a good thing that you like to tinker, so here's your chance. One thing to remember, is that there is no one best setting, so you will have to keep tinkering as you change programs.


http://www.talkshopbot.com/forum/board-admin.cgi?action=quick&do=print&HTTP_REFERER=29/26478&postindex=61433

[porscheman]

John,

Your post doesn't mention whether you have a PRT or PRT Alpha. If you do have an Alpha, Shopbot has a something called an "alphaStep Driver Updater", which is a special cable and executable PC program that allows you to effectively double the stepper resolution of your existing motors. Basically, you reprogram the drivers (black boxes) inside the ShopBot control box. Ted Hall was gracious enough to tell me about this "unadvertised" item at Gary Campbell's camp last February. It took about 5 minutes to perform the procedure and change the unit values in the SB3 software. This process can also be reversed, if you are not happy with the result.

I performed this upgrade on my well-used PRTalpha, and at the same time followed Brady's ramping value suggestions in the article mentioned by Thomas. The improvement was quite simply jaw-dropping - I couldn't believe how smooth, quiet, and "crisp" the machine was after that. A new set of pinion gears brought the machine to what I consider like-new condition, and I didn't have to spend big-bucks on upgraded 7.2 motors (though I still spent the money on other Bot stuff.... :-)

As Thomas (and Brady) point out, the only changes I make now is to alter my ramping values depending on whether I'm cutting 2D cabinet parts or 3D carving work.

Regards.

John

[jdgrahamwaldorf]

Thomas, Thanks for the link, I remember reading Brady's column when he wrote it but had since forgotten it. I will definately start with playing with the software.

John, I have a standard machine and while switching to an Alpha system is an option my goal with this thread is to get the best possible machine with the standard/4G setup.

Thomas' reply,and my ommission, highlight the fact that there is plenty of info on this site but it is sometimes hard to find it or to know if it applies to your machine. After reading the recent linear rail post, always seeing posts about the Alpha / 7.2 motor upgrades, and the new standard controlbox / motor combo I thought a new thread might help steer me in the best direction to improve my machine.

John