surface grinder roller-ways reconditioning

Hi,

I have a surface grinder will roller-ways (brown and sharpe 510). The rollers
run in a flat way (front) and a inverted v-way (rear).

The table was scored by incorrect installation of the rollers in the v-way; the rollers didn't roll, but rather the table slid over the rollers. Since the rollers were hardened, the table lost that battle.



The scoring is about .005" deep. It doesn't affect the whole of the V-way, think of how a cylinder running parallel to an inverted V-way and it'll be clear that it would score a channel on each side.



This picture shows the underside of the table, with the rollers and cages in their approximate position. At the bottom left in the v-way channel you can see the score line.

I called around some grinding shops and the one I found that had a machine that could grind a 30" long table said the job would cost more than the grinder is worth.

Are there techniques for doing this by hand? Scraping would not seem to be appropriate, given the current surface (where undamaged) is smooth and intended for very high precision rollers (.750" to .000050" tolerance) to run in them.

I took a glance in the Connelly book but didn't see anything about such surfaces.

Obviously keeping the height of the inverted v-way relative to the flat way is pretty important.

At the extreme ends of travel I seem to have untouched surfaces which can probably be trusted to show the original relationships between the V and the flat ways.

Phil

This is one of those times where a very smooth hand scraped finish is desirable. With a very large radius blade and shallow angle of attack you can achieve super smooth finish, ie TIR of a 0,0001" or so, it almost feels like glass with zero texture to the touch. If you wanted to go the last step you could perhaps lap for final finish, but Im not sure youd need to. Am pretty sure theres something in Moores book iirc, will have a look.

Surface finish is a bit of a contentious subject in the scraping world, my view now is theres a time and place for depth or super smooth.

Cheers
D

Maybe look to a second opinion for grinding?

I have done similar grinds for guys with great success.

The Kinetic Co., Inc. on Instagram: “We are grinding some ways for @chiefbub These are for a his MHT grinder that has ball bearing roller ways. Just need to dust a couple…”

The Moore book has some very nice discussion, i’ll Have to reread it carefully.

Any idea what a grinding job like this should cost?
I’ll also ask B&K if they can give me the print for the
Table geometry.

Thanks,
Phil

I have scraped a B&S like this a couple of times. The flat didn't have a .005 gall in it though. It is complicated for an experienced scraper let alone a rookie. What Cash said sending it out to be ground would be a good way for a rookie to unless you have a lot of time on your hands. You didn't say if the base flatways are scored too? If you had me do it, I would first rough scrape the ways .005" down )both sides or send the table out to be ground to clean up the .005"

Then trig out how much would be (its called vertical rise, but your lowering it) ground or scraped off the V's to the amount needed to bring down the V's. I would make some ground bars cast iron bars that are the same size as new rollers and wide enough so they covered the ways. Blue them top and sides and rub the top of saddle and bottom of table Then scrape them to match fit the bars that would replicate the rollers. I have done that when I rebuilt some double wheel creep feed crush roll for Sifco used to grind Christmas tree's on turbine fans.

On the B&S grinders made a skinny camel back straight-edge and scraped the ways down on table and base until we were close. Then blued the rollers and rolled the 2 table back and forth then scraping the ways where the bluing rubbed hardest. Once the rollers fit the ways and angles were wiped clean across where the bluing rolled off evenly we stopped scraping and then used some Timesavers lapping compound to remove the depth of the scrape marks. I think I still have the straight-edge as a matter of fact.

I am guessing grinding would cost $1000.00 and $5000.00 to scrape it plus the bars and rollers. A guess of another $2000.00 This and not scraping the column and saddle. If you wanted to save some money we could possibly order the rollers for the flats .010 bigger and not touch the V's.

I'd think you could just stone the high spots off next to the gall, replace the rollers and be good to go. The best surface in the world won't help if the rollers are damaged, but all the V needs to do is support them and provide a smooth rolling surface. Holes and scores shouldn't matter.

The sliding rollers may have not done as much damage at it appears. I would map the area excluding the far out side of long travel to see how flat it might be. It may be near flat for the area excluding the out most rollers.

QT:[I called around some grinding shops and the one I found that had a machine that could grind a 30" long table said the job would cost more than the grinder is worth]

That answer is just plane dumb, how does he know what the grinder is worth to the owner. Restored to top condition one can hardly find a better grinder.
Far better answer would be xx number of dollars.

Ok, what happens if you just make sure there is no raised metal and reinstall the rollers properly? Yes, there is a small area where there is no material supporting the roller. But the majority of the roller support is intact (and unused).

Taking another look at those pics, if youre happy with the geometry of the machine and the rollers are sound, a good deburr and put back as is might be the way to go. That groove isnt so wide and its 'the right way in the right place', you might have lost 10-20% bearing but those rollers wont be riding down into the groove when they are put back right. Keeps a pile of time and money in your pocket.

Had a quick look through FOMA, Page 25 briefly talks about scraping depth and applications. Further on theres a big section on lapping, at a glance it seems they only lapped hardened materials after grinding. Interesting stuff.

Brandenberger said:

The Moore book has some very nice discussion, i’ll Have to reread it carefully.

Any idea what a grinding job like this should cost?
I’ll also ask B&K if they can give me the print for the
Table geometry.

Thanks,
Phil

Click to expand...

If the ways unbold like the ones I did for Chiefbub off the top of my head I think that was about a $500 grind- off the top of my head, this is a pretty straight forward grind. I am quoting SB lathe beds at around $1,250.

B&K probably won't give you much info. if you call there talk to James Hunt.

Thanks all for the discussion.

To answer a few questions: the flats are NOT scored, just the V. There seems to be a few tenths of wear if that on the flats in the center. I think the flats were poorly lubricated but still rollers were rolling.

These machines in good condition in this area are going for $500-$800 it seems, I have seen 3 for sale in retiring machine shops. So that’s how I judge the ultimate value vs cost of a re-grind.

I did buy a set of replacement rollers still in original packaging from a shop shutting down, I also made some from case60 linear shafting prior to finding the replacements.

I have stoned the female V way, and there is about 50% undamaged width in the worst central section along the V-way. The rollers have more of a tendency to “rock” under lateral pressure, but of course with the table and mag chuck weight bearing down, and 8 rollers engaged, they probably work together to minimize this effect.

Maybe I need to sign up for a Scraping Class and bring this table as a project!

Thanks again,
Phil

QT:[These machines in good condition in this area are going for $500-$800 it seems, I have seen 3 for sale in retiring machine shops. ]

For flipping machines perhaps 300 to $3,000. but for using a surface grinder the B&S is a world class machine so one in very top condition would compare to perhaps a $12.000 new machine...

Most often a accurate (tenths running) SG is hard to find under $1000 IMHO.

I have it's big sister, 612 Valuemaster B & S SG. Will say mine was in good shape for the ways and rollers, too, for the amount of crud and grime I cleaned out the SG when I got mine. Mine was also equipped with a continuous feed oil lubrication system, which probably saved the roller ways from destruction. If your SG did not have the continuous oil feed system, maybe something to consider adding once the reconditioning has been done. Ken

cash said:

If the ways unbold like the ones I did for Chiefbub off the top of my head I think that was about a $500 grind- off the top of my head, this is a pretty straight forward grind. I am quoting SB lathe beds at around $1,250.

B&K probably won't give you much info. if you call there talk to James Hunt.

Click to expand...

That is extremely affordable for a lathe bed grind!

I might add that a surface grinder of that quality and ability will likely never be made now or in the future. likely that machine would cost $20K or better if made today.

The wheel head casting moving gave the most solid and right angle ability. The motor being belts to the spindle gave vibration free for best surface finish. I ran a B&S Micromaster that would make ring-together parts and run tenths like they were easy.

Draw back is that belts spindle drive is not as good for out-right hogging and rollers and balls machines should be tore down every few years for cleaning so not as long lived as scrapped iron oiled long travel ways.

Turcite and the like is good but not as long-life as iron/oil ways IMHO.

If one paid $3,000 (or even more) to rebuild such a machine it would be better than likely any SG made today.

Dear Phil:
I know this is not exactly what your post was about, but I thought you would find it interesting. This is my family’s company. We invented the Dunbar Roller over 50 years ago and Dunbar Rollers are installed in thousands of surface grinders. Take a look at our website here:
Welcome to Dunbar Commercial Enterprises
It’s an excellent and economical solution to increase your productivity and maintain tolerances. We would be glad to answer any questions you have! Contact us through the website or directly at [email protected]