New from Tennessee

[Bank Walker]

Just wanted to introduce myself. I bought a 4x8 shop bot a week ago yesterday. Might take a while to reassemble and get it back operational. I am sure I will have lots of questions for the group.

[Bank Walker]

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First of many pictures

[Brady Watson]

At first glance, this appears to be an early PRT 4G - looking at the AL extrusion on the gantry, CNC bent legs and gussets.

There are several non-factory parts on the machine that I can see - The X rails are Bishop-Wisecarver (BWC) but are tacked on to the AL square tubing in a horizontal configuration. Hardened rails are better than stock, but that wasn't the best way to pull it off.

The stepper motors (at least the one on the Z) is not factory & I cannot tell if it is running gear reduction. It doesn't appear that it is - and that means very coarse movement and not a lot of torque.

The cable carriers are a nice addition - not factory though. Most problems with these machines stem from poor wiring management.

Post more pics - including ones of the control box electronics, and I'll do what I can to help identify.

Welcome to the SBF.

-B

[Bank Walker]

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[Bank Walker]

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[Tim Lucas]

Welcome !!

[Brady Watson]

Hopefully you paid pennies on the dollar or got it for free...Somebody did a LOT of hacking on that machine & I wouldn't say it was for the best. I am not someone to blow sunshine - so I'll tell you the truth. This machine *could* be a decent reliable machine, but you're going to have to put some money into it. You basically have a blue frame with a ShopBot sticker on it. It's a lot like buying a car as a rolling chassis...

The Y acme leadscrew (not even anti-backlash) isn't factory, nor does it belong on any CNC. Neither are the controls - appears that someone pulled all the SB controls and downgraded to a parallel port based control software. What a shame. It doesn't appear that any of the high quality stock Vexta steppers with gear reduction are on the machine. They broke/cut the gantry where the stock X motors would go...so there's some welding to be done too...

You're probably looking at $3k minimum to get the machine in working condition where you could rely on it - on a shoestring...with you doing all the labor. You need a modern control box (maybe could reuse the motor drivers but they're old tech), new motors with gear/belt reduction, or you'll have no torque or resolution, take off the Y screw and replace with rack & pinion. Any less than this & you'll just have a boat anchor and you'll be forever frustrated. You could spend a little more and replace all the junk with real linear bearings...and a spindle instead of that Porter Cable, which may need brushes and bearings as it sits.

Don't want to come off all doom & gloom but I've wrenched on more than my fair share of these machines over the years...

-B

[srwtlc]

All I can add to what Brady has already stated is "Oh My"!

[Bank Walker]

Well, not sure where to start that is best. No need to get angry or frustrated yet. No since in getting upset. No, I did not pay much. Nowhere near a new machine. I realize there are much newer and much higher tech units available. I knew it was older when I bought it. I watched it run. He used it mostly to fabricate cabinets and cases for sound systems. While I was there he used it to turn a 1x12 into a box with predrilled holes, bottom groove and dovetails on the sides. Yes, it is slow but plenty fast for my needs, maybe. I plan to use it to cut 4x8 sheets of material and engrave signs. Considering I am starting from nothing, it is a start and gets me straight up to 4×8 size.

I will need to reassemble, get it wired back up and running. Then see how well it will work for my needs. Then upgrade, change out as needed. No stress.

It has Mach3 and Lazy Cam with it now. So, I will be looking at upgrading that also when I get it all up and going and need more design capability.

[Bank Walker]

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This is my weakest mechanical link. If i can replace this welded piece of angle iron with the 2 nuts for proper cnc equipment I feel it will greatly speed up the machines performance. At higher speeds above 100 inches per minute it would flex the 2 away or towards one another causing chatter in the units operation. I have no clue what should be there or why it was replaced with this instead of something factory OEM ? But, it is and we will fight this one battle at a time. Again, no stress. Maybe, this entire ball screw setup will be swapped out instead for a rack and pinion before i change the control system. Time will tell.