knife grinder STEEL way groove repair, scrape?

Some things to think about/consider based on what has been previously posted.

There is wear on the surface supporting the band from rust and grinding particles allowed under by lack of grease. I would assume this is greatest in the middle of the span as this is where the band could lift the most. It may not be uniform across the 1 1/8 width of the band. If the "sholders" of the slot are not worn this may give you a surface to measure off of. The bottom of the band should also be worn. The top of the band shows a wear strip not extending to the edge, If you can measure the dept of this wear with a feeler gage or depth gage and mike the strip you could determine how worn the strip is vs how worn its base is- though not sure if this will be helpful or not.

Rich talks about a fix he did in post #7. It sounds like it took a while. A temporary fix to consider would be using feeler gage and shim stock to bring up the surface of the band to level. If possible before adhering in place- grind a knife or strip of metal you can inspect with straightedge and adjust shims until results acceptable. To adhere the shims I would consider something you can have seep in along the edges with the shims in place and the band weighted down. This way you are not taking it apart to apply adhesive and having the adhesive change the thickness. The shims are trapped in place by the slot and the band. All the adhesive needs to do is keep them from shifting and overlapping. It could also seal out any grit. What adhesive to use? My initial thought was to talk with West Systems Epoxies. They make hardeners for use in cooler temperatures. You would want a flexible epoxy. Even with a low temperature hardener, there would be some flow prior to hardening- and after mixing there is a limited time to get it applied. Another thought is to talk with Loctite. I know they make a penetrating threadlocker to apply to assembled threaded parts. It --might-- or might not--- be possible to use another of their products then make the area it was applied anerobic with a layer of argon from a TIG welder bottle. Never tried this- anyone know if it works? Argon is heavier than air- so a dam could be constructed around the area to hold it in place.

On this they're looking for as permanent fix as is reasonable. Shims probably won't work because the way material has virtually no rigidity and relies on the groove "floor"? To hold it flat and straight. Even small bumps and spaces between shims and thickness differences would show up on the parts being ground.

As far as epoxies, I think those are going to be a possible way to fix it, I will know more after I get a better look at the wear. Those way strips have been replaced in the past, but it has been several years.

Good food for thought there, thanks for your time and suggestions.

When we restored Cincinnati ball racks by grinding we first called Cincinnati to find the depth of hardness. I believe they said 035 or .040

I found a Camelback that would work for you. It's a King-Way Brand Straight-edge. I have had it for 60 years. My dad made it to scrape a crankshaft grinder. It was 2" wide but he needed a thinner one. It's 1 1/2" wide. It was scraped years ago and I've had it in my rack for years and never used it again. I could drive 1/2 way and meet you, you pay me. It's 591 miles - 10 hours. round trip. Have to buy me lunch and pay me 2 tanks of gas I could check it on my granite and touch it up if needed. If its within .0005" flat that should be good for the slot. Make it flat and not a lot of points. Here is the size 1 1/2" wide x 10" high x 72" long and it weights 60 pounds. I also have a 36" x 2" wide x 7" high 28 pounds. It's a older model, not sure the brand. also was machined and would need a touch up scraped. a 2 1/2" x 49 1/2 and its a heavy one 90 pounds, and I have 3 King-way brands 2" x 8 x 35 1/2 - 24 pounds. 1 is a casting, one was scraped but now rusty and one that I just had machined. PM me and I'll give you a price. I would think the HK 72 King-Way brand would be best. I could drive out tomorrow with it if it doesn't need to be scraped. Otherwise Thursday.

Pm incoming Mr King! Not that big of a hurry either, inspection is Wednesday but repairs will be a week or two out, minimum.

alright everybody, I did the inspection, maintenance ( just some of it) and rust removal, LOTS of rust removal. I didn't get a picture of the rust under the way, just too busy. This is just the front way groove and from my measurements isn't actually too bad, around .003" over the entire length from highest to lowest spot (although it was hard to measure with the saws beneath us my indicator being mounted to the head bounced .002"-003" and the bubble in my level bounced 2-3 divisions. 0003" per division, per ft) we scraped the rust out and off of what we had apart which was the magnet fence and the front way. I followed up with my hones. we didn't have time for the rear but it measured much flatter after doing the front. I had the operator grind the magnet for temporary use because in at least 5 years (more likely 10) it hadn't been done and was really badly warn in the middle. we found a host of new problems pop up during the inspection as well, the head randomly drops (hoping just sticky ways) the wheel wasn't being dressed, the coolant is being guess mixed, and very little lube added to most of the machine.

the machine level was off .005, but fairly consistent from end to end.

there is still a lot to be done but it'll be a week or two now before I go back since it runs much flatter and my jobs are backed up.

thanks to everybody for your help and suggestions!!

An Update: HV and I talked on the phone. He is really sharp young man (40's, is young for me. lol) and runs a family machine repair shop he took over from his dad. Much like me. When I called his daughter answered the phone, he said she (20's) is a good machinist too. He is going to buy some used straight-edges from me too. We talked about his project and I'm volunteering my advise. I will help anyone as long as they are receptive for help. Not like the ones I have on ignore that is. This will be a great thread for all to learn. Merry Christmas.

Thanks for the kind words Richard! And thanks for the nice chat and sound advice.

I look forward to putting the tools we discussed to use.

Thanks again.
Jacob

Thats a knive grinder with a magnet isn`t it
The ways then need to be parrallel to the magnet more as straight
If the magnet has a curve any knive on it follow that curve So the grinder head has to follow that curve as well
Perhaps you can fill the ways with a slow curing epoxy and make a scraper of some kind running over the magnet scraping the epoxy in his non cured state

Peter

Peter from Holland, interesting idea, I'll have to keep that idea in mind. This project has been kicked down the road a few weeks since we got it running a little better.

Thanks for the suggestion.

Jacob

At least I would messure it that way
And check how straight the magnet is Another remark Can you grind the magnet once you are done Or have they done it already with the worn ways making the magnet not straight anymore And how straight does it need to be according factory specs
Peter

hvnlymachining said:

I was able to peek under the ways by lifting them with a magnet and using a flashlight, there was rust and wear visible, also some amount of abrasive from the grinder. It hasn't been cleaned under there in years.

I wasn't too crazy about the idea of scraping in there anyway. But lack a good idea of how to get a good true surface inside that groove.

Thanks for the tips Richard! I'll be re reading these Wednesday while inspecting!

Thanks for the kind offer of the level, but yes I do have a master level and a larger 27" long Bullard level that reads 0.0003" per ft. I figured this would be long enough to avoid needing a parallel across the ways.

The area I lack tooling is I don't have a very long camelback straight edge, but I do have a 8' suburban tools steel straight edge I will take along for inspection.

I will ask about a manual, and I took those photos ( terrible I know) it was just turned off for me to take a quick look so we didn't have time to remove anything on Friday.

Thanks everyone for your time, I will keep you posted.

Edit; Richard, in your opinion should I be rounding up a couple of longer straight edges for this job? Or is there a workaround that's satisfactory for a job like this? Thanks.

Click to expand...

"I wasn't too crazy about the idea of scraping in there anyway. But lack a good idea of how to get a good true surface inside that groove."

This idea may be totally off the wall but could you use epoxy, Bondo, or whatever and make the true surface by putting a thin band on top and tensioning it so it is dead straight? I'm thinking temporarily mount precision blocks (1-2-3 blocks?) at the ends to ensure that both ends of the band are level and in the same plane.

May be totally impractical but I thought I'd throw it out there anyway.

This idea may be totally off the wall but could you use epoxy, Bondo, or whatever and make the true surface by putting a thin band on top and tensioning it so it is dead straight? I'm thinking temporarily mount precision blocks (1-2-3 blocks?) at the ends to ensure that both ends of the band are level and in the same plane.

May be totally impractical but I thought I'd throw it out there anyway.
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Actually the way material is a tensioned band, I agree with you that Bondo of a sort of an epoxy is probably going to be the best way to fix this machine. I think scraping or grinding the filler material will be required to get a good true surface beneath that band though.

While doing inspection on the machine I found all sorts of inaccuracies. It's going to have to be a multi stage rebuild for sure since they can't have it out of service for more than a few days at a time.

Thanks for the suggestion.

Jacob

Bondo will be too thick for the tension of the band to push it out in time before it hardens. If the machine is around 40F then 5 minute epoxy will work, if 60F I would use some other 15 minute epoxy to give you enough time to work.

If you just have a few low sections then the band will be very flat, but if you want to lift it over say, a 3 foot section, you will not be able to pull the band near hard enough to make it as flat as the standard wire drop tables for 30 pounds on a piano wire. Use shims to hold it up, I'm guessing you want one every 18 inches.

Bondo or an epoxy with a lot of fillers could be used, if you apply say, a 1/4" square string of bondo, set the band on top of it, then set a 6 or 7 foot long straight edge on top of it to flow out the bondo, then tension the steel strip.

Mold release on the strip might make it removable.

I have repaired one of these grinders and explained how I did it in the first few posts. I used Moglice "Score Ex" and a product sold in auto stores called "liquid lead" which smells and looks like Score Ex and fiberglass epoxy (it's a lot cheaper too). Another product that would work is Devcon Plastic steel. The secret is to clean out the rust and debris in the rusted groove. It will also be wet with coolant oils that need to be sealed out, compressed air and I would suggest brake cleaner or some sort of degreaser before pressing it into the worn areas with a wax released cast or steel bar, then sand or router out the access that is higher then the original surface. That is how I did it and the next year the maintenance tech at the wood processing plant did another machine the same way. I'm not guessing like many of you are. I would also suggest after he has the groove repaired he spray it with some sort of spray lubricate that dries so the remaining exposed steel doesn't rust again. He and I spoke on the phone. I suggested he tell the paper mill to order new stainless bands. He said they did and are back ordered. I also have sold him some used cast iron straight-edges so he can check the height of the new repaired surfaces and the worn banding. I would suggest if you have repaired one of these machines you tell him how, if not, not to guess.

Richard, as stated, has given me some great advice, that I'll be putting into use.

Using the band to flow the filler would be difficult considering the accuracy needed and a large part of the length will need repairs. I'm afraid it wouldn't end up nearly flat enough.

Thanks for the input.

Jacob

I missed Peters question earlier, so here goes. The magnet was only ground after my inspection and (some what) repairs, so that they could use it. A magnet can be re ground many times as long as you don't grind it too thin which varies from magnet to magnet. As far as accuracy, the book calls out about .0003" on the ways over the entire length of the machine. But the customer would be happy with .003"

hvnlymachining said:

But the customer would be happy with .003"

Click to expand...

Richards method of filling the slot and then sanding it flat within tolerance will certainly work, and the steel strip will be removable.

Using a straight edge's weight to press out a thick material like Bondo will also work but the strip will not be removable unless you spray a reliable mold release on it... In which case you can still remove the strip, cut a groove on both sides, then sand the Bondo down if it isn't flat enough.

Seems to me it's a lot less work to start with something already flat to .001" over 6 feet than to trust any other part of the machine to scrape the epoxy flat and then use the straight edge to make your corrections

Johansen, your method could work too, I just don't want to risk damage on the ( flimsy) way strip since they're not available. If a filler happen to stick it could be troublesome.

Jacob