Broke a V roller

[coach]

I just ordered replacement V rollers for my bot.
The v roller on the top rail broke this morning.
I heard a noise and discovered pieces of it on the rail. little bearings laying under the e chain. I actually have 2 of them damaged but believe the 2nd got damaged from running over a piece of the first.
Frank at shopbot said he has never heard of this happening.
Of course I have work for the bot so I had to order overnight for Saturday delivery....OUCH!! ! !
Wondering if anyone has heard of this happening.
I have a prs alpha about 2 years old.
Thanks for any input.
David

[Brady Watson]

I've never heard of this happening in the history of ShopBot or BWC. The big question is: Are the rails damaged? The wheels are supposed to be hardened stainless, and the rails are either hardened stainless or hardened steel, depending on when your machine was produced.

-B

[coach]

The new ones will be here Saturday morning. I am going to take a good look at things then. The rail has a slight nick but nothing too serious.
I think the nick is from running over pieces of the roller.
The prs alpha was bought new July 2007.

[erik_f]

Brady,
How do you know if your machine was produced with stainless rails?

Erik

[erik_f]

It looks like on my BT the X rails just say T-2 and then the ones for the Y say T-2SS...I it would seem to be the x have carbon steel and the Y has stainless?

[Brady Watson]

David,
A little JBWeld in those rail knicks will patch them up nicely. You will want to fill & fair them so that the 'bump' doesn't transfer to each & every cut you make in that area of the table.

Erik,
If you've got the SS rails...you've got them. If not, the regular hardened rails are just fine. Heck, my original PRT angle-iron based rails look almost as good as the day I put the machine together (2001). They are not hardened (but also not CNC bent malleable steel like the newer pre-PRS tools).

-B

[erik_f]

You're right...either way its fine...but SS is just so much more fun to know is on the machine.

[coach]

Brady, Thanks for the repair advice.
The v rollers are not stainless.
The one that broke almost looks like "cast steel"
(not to be confused with cast iron)The area that was fractured is grey and reminds me of cast.
My magnet tells me none of my rollers are stainless.
I figured out how I did this.(I think) It was absolutely not a defect or inferior parts. I am going to post in a different area so more people can read of my error and maybe not do the same.

[cutitout]

We had one bust on the SIPs panel Shopbot that I helped run at my day job. -- so yes they can brake. (the machine had been moved several times and is was a 8x24 seen in the videos on Shopbot's web page)

[dubliner]

David, Have you posted your diagnosis of how the V-roller broke yet, I'm very curious how we can avoid the mistake, if it was indeed yours.

[coach]

Neville, I actually posted it under the "shopbotter message board."
Here is a copy....I am not completely sure this is how I did it but it seems like it may have caused some undue stress.

--------------------------------------------------------------------------------
I broke my top v roller on my Y car.
I was planing glued up 2x4 cedar boards.
The last board was .150-.180 higher than the rest of the 9 or 10 pcs. I was set up to remove .030 per pass. But at that last board I was well deeper than the cutters. I was running at 8 IPS. I think this caused the damage.
Wanted to share this so it will hopefully save somebody.
Had I Z zeroed at that hi point and brought it into accaptable range....hind sight 20/20

[dubliner]

thanks David, sorry I didnt notice the other post.

[brcguy]

HELP!!!

I also broke a V-Roller, but there is no noticeable mechanism of injury here. I am in a super tight crunch and it's saturday of course. None of these parts are stainless, my rails show a bit of rust (This table is just over a month old!)

This wheel broke cutting the fourth copy of the same sheet, nothing changed. We've been cutting about 50 sheets a day for two weeks. Feeds/Speed finally dialed in and the bit was sharp.

Argh. Anyone in austin, tx wanna save me? I'll replace your wheel on tuesday, or just show up with about 15 sheets, bits and files.

Dave 512.653.3840

[dlcw]

The same V-roller on the top of the gantry car broke on my PRS Alpha 96x60 about a week ago. The machine is about 2 months old. The second v-roller survived because I was just doing a small 3D carving at the time and the Y movement was very limited. ShopBot overnighted a new v-roller last Monday (7/13) and I got it on Wednesday 7-15 (thank you Fedex). I've got about 15 hours of cutting/carving when it went bang.

Not what I was expecting on a 2 month old machine, that's for sure. I hope it doesn't happen when I starting cutting my next job consisting of $100 sheets of cherry plywood. That would put a damper on my day.

ShopBot did get the replacement to me quickly - THANK YOU Frank!

I just wonder if stocking 1 or 2 spare v-rollers of each type used on the machine is a good insurance policy considering downtime waiting for parts is a money loosing - not money making - proposition....

Don
www.diamondlakewoodworks.com (http://www.diamondlakewoodworks.com)

[coach]

When mine broke I ordered a couple extras. I wonder why the reports of breakage. I was told when I ordered mine they had never heard of a roller breaking. Now I hear of a couple in 2 months.
Did your broken area look like it is made from cast steel? Mine had some areas that could have resembled porosity.
Wonder if shopbot got a bad batch of rollers.

[dlcw]

David,

As a matter of fact mine did look like cast steel and not SS. There is very visible porosity in it as well. I wonder if SB got a bad batch of these things and this might be a trend. I also wonder how much SB would charge for a spare set of v-rollers for the entire machine.

Don
www.diamondlakewoodworks.com (http://www.diamondlakewoodworks.com)

[coach]

Don,
I will dig out the invoice from when I purchased mine in May. I will post the price when I find it. I was told these were stainless. My magnet says absolutely not.

[gary_n]

With the breaking of several V-rollers it would seem like a good idea if ya'll returned them all to ShopBot and get them to inviestigate the matter. It could be they are not getting the kind of V-rollers they are paying for.

[dlcw]

At Franks request, my broken v-roller is being shipped back to Shopbot for evaluation.

Don
www.diamondlakewoodworks.com (http://www.diamondlakewoodworks.com)

[gordon]

We're anxious to get the broken V wheels back here so that we can check out the damage. I've been in touch with BWC and they are concerned about the breakage and will get the wheels after we've looked at them to determine why they failed. Their head of development is also a metalurgist and will dissect them fully. We are both investigating whether these are isolated failures or if the batch was bad.

It is the case that up until now the only V wheel failures have been because of outside forces such as, serious gantry crashes with inmovable objects or outside forces like fork lifts or pipes colliding with the gantry or rails. We have shipped approx. 60,000 of BWC wheels since we started using them, some with integral shafts and the earlier ones without. Except for 1 custom order, we have never shipped Stainless Steel wheels. All of them have been made with 52100 Bearing steel. The confusion may be from the Stainless Steel track that we originally shipped with the PRS models. For over a year we have shipped hardened steel track that is harder than the original stainless track.

For those that feel the need to have a back-up wheel, the PRT will need at least one W2X and the PRS a SB-SWIC2X concentric wheel and a SB-SWIE2X eccentric wheel.

I will follow up with any findings that we get after our evaluations and working with BWC to determine the extent of these failures.

[dlcw]

Hi Gordon,

I sent the broken v-bearing via USPS priority mail today. Frank should have it by Friday. I'm anxious to find out what is happening.

How much do the SB-SWIC2X and SB-SWIE2X cost? I'm assuming the C2X is used only on the bottom of the Y car and the E2X is used for all the other locations on the PRS Alpha?

Thanks,

Don
www.diamondlakewoodworks.com (http://www.diamondlakewoodworks.com)

[gordon]

SB-SWIC2X is the concentric studded wheel, they're used on the X and the 2 top on the Y.

SB-SWIE2X is the eccentric adjustable studded wheel used on the bottom of the Y.

They are $29.95 ea. We haven't provided a set for an entire machine so I don't have a price for all 12 concentric and 6 eccentric. If anyone is seriously interested in this I can have a price worked up for a kit.

[dlcw]

Gordon,

Thanks for the update on pricing. Can you work up a package price on 2 of each of the wheels? I'm hoping a lower price can be had by ordering 2 of each versus one at a time.

I don't think a kit of all the wheels on the machine would be necessary, just 1 or 2 spares each for the two types.

Don

[coach]

Has anything been found to have caused this or was it operator error?

[dlcw]

David,

I never heard anything from Shopbot on why my v-roller blew up or ever got a response from Gordon about package pricing. I sent in my shattered v-roller to Shopbot but never heard back from them.

Don
www.diamondlakewoodworks.com (http://www.diamondlakewoodworks.com)