Huge 80 pound, 10 hp spindle on my Shopbot

[robert]

Please help! I want to put a huge 80 pound, 10 hp spindle on my Shopbot. Does anyone know if the motors at either end of the carriage can handle the additional weight? Someone suggested I might use a counterweight and pulley to help the z-axis solve its extra burden.

Anyone have any thoughts, ideas, experiences on this?

[fleinbach]

Why?

[Brady Watson]

Robert,
The appeal of a used/Ebay/cheap Perske/Colombo spindle on a Bot is hard to pass up...however, it is not a good idea. While the X motors can 'handle it' and you *might* be able to counterweight the spindle, you are really adding a lot of weight to the machine. If you are running a standard PRT, then you will have a higher potential for lost steps. You will *definately* have gantry deflection due to the added weight, your X, Y AND Z rails will wear prematurely as well as your pinion gears...Need I go on?

So...it is all a false economy to put a cheap 10HP spindle onto your tool. It *can* be done, but it is not what you want...

-B

[robert]

(to Frank Leinbach) why? Because I carve 4-8"+ thick stone, and machines built for this purpose are typically $100-$300k. I have employed my very beloved Shopbot to carve wood, foam, and even, to a very limited extent, marble and limestone. But cutting stone is, extraordinarily hard on this machine. I love my Shopbot; I would rather upgrade it than kill it with too rough & heavy-duty of tasks. I started this thread with the optimistic hope that someone or someones in the Shopbot community could help me with my, perhaps Quixotic, though quite sincere effort, intended cascade of upgrades.

[robert]

Thanks Brady,
You really think the x motors can handle it? That'd be great. I am not considering used/cheap/false-economy spindles.

The easiest thing for me to do would be to buy Shopbot's 5 hp spindle upgrade, and I have not ruled that out.

I am considering a huge, new spindle: either Colombo or Saccardo Elettromeccanica. I realize there are amazing challenges that must be tackled one after another. Yet, I am likely to go down this path. I have considered it for several years.

This may mean $30-40k in upgrades to me ol' Shopbot. The first step is the 10 hp (+?) spindle. I must think some people on this forum, whether Shopbot employees and/or customers have tackled some, if not all, of the issues attendant with such massive upgrading. So, if anyone reading this has, I would appreciatively accept any and all help. If I go for a 80-90 pound, 10 hp or greater spindle I imagine a cascade of issues including:

1.) (as you say) the gantry carriage would sag, perhaps there would be a 1/16"+? This, I would plan to just live with for a few months after I bolt on the weighty spindle. Perhaps I could even adjust for the sag, by slightly bowing the 3d design of my relief carving to accommodate for the sag.

2.) more lost steps, yes, possibly. Would they be within a tolerable or tolerably predictable range? I don't know. Perhaps I could live with this for some months too. Also-- at some point maybe I would get bigger motors and a replacement control panel. --Maybe get a heavy, cast iron bridge at that time.

I am hoping I can start with the 10 hp spindle, then weld, brace, and otherwise strengthen the gantry. Then improve the z axis with improved linear motion guides and a counterweight. Hopefully, thereafter, I can address other issues and replace other parts one at a time. Does anyone have more thoughts on this course of action?

Sincerely, R

[drodda]

When I was at shopbot about a year and a half ago they had a new machine they were building that had a really large spindle? I am thinking a 25 hp or something like that. they had a really beefy carriage and the table was huge. So I would say that this is not that far of a stretch if you are willing to spend the bucks. Contact Ted and see if they will build it for you?

-D

[gus]

Dave, you must have seen the one they where making to cut the foam filled wall panels for building homes. I saw it when I was there. Very impressive.

[richards]

Robert,
Talk to Ted. I'm sure that he could either furnish you with a customized vertical gantry (that would probably not flex as much with the heavier spindle as the horizontal gantry that you now have flexes), or he could suggest ways to strengthen your existing machine.