Any PRO4848 Common Problems?

[dbcheek]

I am looking at a used PRO4848 this weekend to purchase and this will be my first experience with cnc. The unit is 4 years old and looks like light use. Are there any main wear/tear items I should inspect, or to tell if it was assembled correctly? The owner is using VCarve Pro/Mach3. Are there any diagnostics I can run in those programs to test if it is dialed in correctly? Thanks for any help!

Similar Threads:

• Common Chinese Co2 Laser Problems & Solutions
• TL15 Common Problems
• Some Common Problems of Laser Engraver and Solutions
• Common Machining Problems

[PapaLima]

I'm sure others, way more experienced, will chime in but I would check a few things.

the belts from the motors to the gears
check to see if the gears and rails are in good shape
feel the rails and see if they are dry or have a very thin coat of grease
Do a homing sequence and listen to it while it is moving and make sure it sounds at least consistent in X and Y.
See if you can cut a larger square ( take some wood of your own ) and check the cut square's edges and make sure it came out square and the lengths are correct.
At least then you will see the entire process from Vcarve to Mach3 to Cut if you have never seen it before.

It will be a bit of work to get it apart and back together again. Probably obvious but try to label all the cables, etc before you dismantle it.
I would download and read the installation manual before hand if you can.

I couldn't be happier with our Pro and find them to be really pretty beefy machines.

Any idea why the person is selling it?

[wmgeorge]

Take along some plywood and have him rout a square of a certain size and same with a circle. Belts can be replaced, if it can't cut a straight line or circle thats something else. Who did the control box and is the a diagram for it and what is being used for a router motor or spindle does it ramp up and down ok?
PS and don't count on the software license being included for VCarve or Mach3

My guess he is selling to buy a bigger machine

[ger21]

At 4 years old, this is probably an older V Rail machine? Check the square steel rails for uneven wear. I recall some people having trouble getting them properly aligned.
Also check the pinions for wear.

PS and don't count on the software license being included for VCarve or Mach3

A Mach3 license is non transferrable.
But Vectric licenses are. If V Carve is included, get the license number, and contact Vectric to see if it can be transferred to you. I think there's a $50 or $75 transfer fee.

[dbcheek]

Thanks everyone for the advice! There was good and bad with the machine. Seller said he was selling because he doesn't use it enough, he has moved on and is more into 3d printing for RC boat parts. He claims it has less than 100 hours on it. He's a retired engineer and seemed to have lots of hobbies and not enough time for them all...

We cut an 8" square and measured it with his Mitutoyo caliper and it was 8.020" on one side and 7.985" on the other which seemed pretty far off to me. He had not been striving for any better accuracy so had not noticed it. He is going to adjust it and I will test it again. He said it was adjustable in Mach3 is that correct? He did trailer it from Florida to SC after he built it because he moved, so I'm guessing that affected the accuracy?

More concerning to me was the speed. I asked him to demonstrate the rapids which the specs of the new model say should be 1200 IPM. He drew a 38"x38" right triangle in VCarve and had it "air cut" that pattern set at 1200 IPM. I timed the perimeter at 19 seconds which I calc to be more like 400 IPM. Was that the correct way to measure the rapids speed? He did not seem to ever have tried that before. Would the linear rail upgrade in 2016 affect the speed that much? Please see the attachment - I am guessing it's the older V Rail that was mentioned? Does anyone know how much the upgrade kit is? I've heard it's offered but I couldn't find it on cncrp. Thanks again everyone!

[dgage]

If you’re looking at those sorts of rapid speeds, you need to buy a better machine, an aluminum machine will not cut that fast and probably won’t move that fast reliably. The aluminum machine with wood base simply doesn’t have enough mass to handle that speed. And the machine is also too small to make use of that speed but to answer your question, acceleration may make a greater impact than top speed. A corollary would be like putting a Ferrari on a go-cart track, the Ferrari will never be able to use its top speed.

For me, that looks like a decent machine that should work well for DIY usage. And you should be able to get it more accurate but really, you might want to think about converting to linear bearings, which would be much more accurate than the V-con rollers. You could contact CNCRP and ask them what it would cost to upgrade that size machine. This would give you the chance to rework it and ensure maximum accuracy I’d thats what you’re looking for. The current owner has already proved it works.

[ger21]

We cut an 8" square and measured it with his Mitutoyo caliper and it was 8.020" on one side and 7.985" on the other which seemed pretty far off to me. He had not been striving for any better accuracy so had not noticed it. He is going to adjust it and I will test it again. He said it was adjustable in Mach3 is that correct? He did trailer it from Florida to SC after he built it because he moved, so I'm guessing that affected the accuracy?

Lot's of things can affect the accuracy that you saw. Moving the machine is not one of them.

1) The machine may have never been accurately calibrated, which is needed.
2) Material, feedrate, cut direction, tool sharpness, and machine deflection can all contribute to accuracy errors.

A skilled operator can work around all of these issues to get accurate parts

More concerning to me was the speed.

Couple things here. It's only going to go as fast as Mach3 is configured to go, and I doubt that it's configured to run at 1200ipm.

Then you have to allow for acceleration. Most of these machines that are configured to run that fast have fairly low acceleration settings, which means they can take 1-2 ft to reach full speed. In almost all cases, you'd be much better off running at 600ipm with higher acceleration settings.

If the price is right, that's a decent machine.

I'd also look at upgrading to linear rails, but it could cost about $1000 or more?? (just a guess)
Linear rails won't afect the speed, but they will make it more rigid, which can increase accuracy, especially at higher speeds.

[dbcheek]

Thanks! I will likely upgrade if the cost is not too much - waiting to hear from cncrp. Here's a closeup of the rails (not sure why the upload rotate it). Does anyone see any uneven wear? I'm not sure what I'm looking for there or with the pinions. There was vey little grease on them, but he said he had not used it in the last 6 months. The belts felt new but had ~3/16" deflection - is that to spec?

wmgeorge - it was the Nema 34 pnp kit and he's using the Bosch1612 router. That all sounded fine to me.

[dbcheek]

Thanks, Gerry. Anybody got a feel for "the right price?" I never see these for sale around here, so it's hard to get a feel. He's asking about 80% of new.

[ger21]

A current Pro 4x4 with Nema 34 electronics is about $7000.

It's used, and it's the older style, which is not as rigid as the current linear rail machines.
I'd offer between $4000-$5000.

[wmgeorge]

Was the square he cut square? The circle a true circle? Yes the steps can be corrected in the software, might just need a tweak. My 48x48 Saturn 2 from FLA with a heavier steel gantry I run at 600 ipm rapids but it rarely ever gets to that speed. It also has NEMA 34 motors. I have no idea of the used cost but I think 80% of new is kinda high.

The control being Plug & Play pre wired is a big plus over Joe home guy design and build. I am sure its ESS Ethernet control which is another big plus.

[ger21]

but I think 80% of new is kinda high.

I agree, as I would not want to pay 80% of new. However, if the alternative is buying new, 80% is not that bad.

It does look nearly new.

The fact that the new machines are greatly improved with linear rails to me would knock the value down to the 60%-70% range. Since it's nearly new, he'll want to get as much as he can out of it.

[Gary-Wiant]

If he is stuck on the price tell him to deduct the cost of the upgrade including shipping & I'd ask CNCRP what the selling price was as back 4 years ago.