Thread: Grinding a narrow deep relatively slot .600 deep by .140 wide

Attached see photos of a one-off (possibly a few more) project I am finishing up. It will be a snug for a DTI and will attach to a planer gage and other devices. It is made of 0-1 tool steel hardened to 50C. The brown color is the result of the oil quench and will eventually be ground off.

The insides of the slot are very nearly parallel but are off by about 1-2 thou with the narrow portion at the depths of the slot. This variation was, not surprisingly, due to the heat treating process. The slot is .140 wide and will go to .144 when finished. I am wondering what stone to use on my Harig 6X12 grinder to make the walls of the slot more nearly perfectly (+/- .0003 ) parallel. I am concerned that taking say a 1/4 wide stone and reducing to .135 for .620 on its radius results in a pretty fragile stone which is only compounded by the need to relieve a few more thou to within the last 40 0r 50 thou as I will need to side grind on that protruding portion of wheel. I have not needed to grind such a narrow slot before and so I am wondering how to proceed.

Seems like an abrasive-plated disk would be ideal but am not sure where such would be found. Diamond should not work well in this application. Borazon should work but is pretty pricey. Maybe others have thinned down a stone in a similar way to what is worrying me.

I'd appreciate any experience you can offer.

Denis

Thinning down a 60 grit wheel to .135" shouldn't be a problem. I've thinned down Norton 32A's to around half of that before. You've pretty much listed what to do...thin to about .010"-.015" under the slot width & relieve all but about .05"-.08". Since you only have .002"/side to grind away, moving in .0003"-.0005" per pass on the cross feed should get you to your target easily. The only thing to really watch for is the rim of the wheel loading up while you transverse. If much more stock had been left, I would suggest plunging the wheel straight down slowly through the slot instead of using the cross slide. This would put the load on the periphery of the wheel instead of the side. Heat buildup from side grinding much stock would give you fits also, or at least it does me.

Thanks for the "green light.". I just did not want the stone to blow up and then realize that I should have asked first. It would seem that a light touch with a thinned stone is good idea. You can be sure I will be double-checking position as the stone approaches the work. I will.be using coolant too.

Denis

Originally Posted by toolmaker35

Thinning down a 60 grit wheel to .135" shouldn't be a problem. I've thinned down Norton 32A's to around half of that before. You've pretty much listed what to do...thin to about .010"-.015" under the slot width & relieve all but about .05"-.08". Since you only have .002"/side to grind away, moving in .0003"-.0005" per pass on the cross feed should get you to your target easily. The only thing to really watch for is the rim of the wheel loading up while you transverse. If much more stock had been left, I would suggest plunging the wheel straight down slowly through the slot instead of using the cross slide. This would put the load on the periphery of the wheel instead of the side. Heat buildup from side grinding much stock would give you fits also, or at least it does me.

Well I followed the advice I was given above and it worked perfectly. The results are better than I expected with final dimensions of my slot being within a tenth parallel and crisp planes. There was no hint of complaint from the wheel I used----an originally ¼ wide 32A 46 I (because that is what I had in a ¼ wide wheel) that I thinned to .135”.


I made a couple of pics but it is not easy to photograph the slot finish in a way that really shows how nicely this turned out. Thanks for your help, Toolmaker35.

Glad to help. 46 grit would have been my choice also, but I wasn't sure what wheels you had to use. Dressing down the width of a wheel is pretty safe as long as you keep in mind how narrow of a width you're wanting with regards to the abrasive size you're using. I've dressed down 150 grit wheels to about .015" before, but wouldn't ever try that with a 46 grit. The abrasive size is too large for so little cross section, or at least that's my thinking on it. I'm glad it worked out well for you.

Edit: I'd forgotten about this. Might be useful later. Also, there's a video on this site showing a wheel getting thinned down considerably.

https://www.hschmidt.com/faq_average_particle.html

Originally Posted by toolmaker35

Glad to help. 46 grit would have been my choice also, but I wasn't sure what wheels you had to use. Dressing down the width of a wheel is pretty safe as long as you keep in mind how narrow of a width you're wanting with regards to the abrasive size you're using. I've dressed down 150 grit wheels to about .015" before, but wouldn't ever try that with a 46 grit. The abrasive size is too large for so little cross section, or at least that's my thinking on it. I'm glad it worked out well for you.

Edit: I'd forgotten about this. Might be useful later. Also, there's a video on this site showing a wheel getting thinned down considerably.

https://www.hschmidt.com/faq_average_particle.html

Thanks, that was an interesting video and the grain FAQ's page was useful. H-S's Narrow Wheel Dresser is pretty cool. The way I did it with a single point diamond was tedious but worked OK. If one did much narrow wheel work, that dresser would be a plus. Cool design. They were talking about thinning to .010.
https://www.hschmidt.com/productcart...?idproduct=197

Denis

I did call National Diamond Lab in Los Angeles today to ask about a better way to thin a wheel than using a single point and taking innumerable 1 to 2 thou passes and yet not spend 650 bucks for a truly elegant tool that would be used only occasionally -- the HS Narrow Wheel Dresser. They kindly listened to my question born of ignorance and recommended a 35 dollar rit dresser. They said it would be much faster than what I did. That is the direction I will be going for now. Good for wheel thinning to rough dimension and then finish with a single point. It will also be useful for roughing a radius or angle on a wheel which I do more commonly.

I must say they have been very helpful when I have called in the past and have provided good dressing diamonds for me at a reasonable price. But their advice is priceless as people say. I have no personal or business connection to them on my part. It's just that when I run into something good I like to pass it along.

I am thinking about getting their NGT-1 unless there are compelling reasons to use something else on my Harig 6X12 manual grinder.

National Diamond Laboratory - Manufacturers of Fine Diamond Tooling

Denis

I'm not entirely sure on how you are dressing your wheel...but we just use what we call a dressing stick. I'm not sure what it is exactly, maybe carbide....it gets hot in your hand eventually, but thats how we thin our wheels and add radius's that aren't critical, etc.

Originally Posted by Bradracer18

I'm not entirely sure on how you are dressing your wheel...but we just use what we call a dressing stick. I'm not sure what it is exactly, maybe carbide....it gets hot in your hand eventually, but thats how we thin our wheels and add radius's that aren't critical, etc.

Boron carbide "Norbide"? (black, extremely lightweight) we use these for roughing in shapes on grit wheels, then single point anything that has to be perfect.

Quick questions for Bradracer 18... Is the dressing stick you use about 1/4 x 1/2 x 3. Is it dark brown to black in color? If so, it may be Norbide stick (or a derivative). I think the only things harder than it are borazon and diamond. I use a stick like that occasionally to relieve and rough shape grinding wheels. My boss has been using the same Norbide dressing stick for the last 40+ years. It's money well spent for roughing a wheel shape out conveniently.

I have had my stick of Norbide for 10 years now.The only wear is right on the corners.If i remember right it was less than $20 when I bought it.

Yep, been using my Norbide occasionally over the last year and it does look like it will last forever. I had read how long lasting they were but it did seem like a lot of money. Then I picked a new one up from someone on PM that had an extra. I have been surprised that it is nearly imposssible to cause appreciable wear.


I did use it some for thinning the wheel but then used a single point to true it up. Nevertheless it was tedious and the Norbide seemed a little hard to control as it sometimes seemed to cut too well. Might be just my problem but I FEEL a lot more in control using a the traverse and lengthwise feed of the table to cut the wheel. Perhaps with more experience I will become more competent and comfortable freehand. Thanks to those that pointed out the Norbide. Nobody uses a grit dresser?

Denis

Looks like a good price on a stick right now would be 50 dollars with a lot of places listing them for more than that. McM has a generic Boron Carbide for 45

Until recently, I'd used the same Norbide stick for about the last 10 years, until I dropped it. It didn't have any appreciable wear on it at all. They're great for roughing down a radius or angle on a wheel. This saves your diamond from the bulk of the wear. They also work great on dish & cup wheels for forming the inside to edge surfaces. A quick trick that I was shown (& wished that I had done, now) is to wrap the center of the Norbide stick heavily with masking tape, just leaving a little exposed on each end. It'll act as an insulator from the heat caused from dressing, and it'll also pad it in case you drop it (like someone I know).

Originally Posted by toolmaker35

Until recently, I'd used the same Norbide stick for about the last 10 years, until I dropped it. It didn't have any appreciable wear on it at all. They're great for roughing down a radius or angle on a wheel. This saves your diamond from the bulk of the wear. They also work great on dish & cup wheels for forming the inside to edge surfaces. A quick trick that I was shown (& wished that I had done, now) is to wrap the center of the Norbide stick heavily with masking tape, just leaving a little exposed on each end. It'll act as an insulator from the heat caused from dressing, and it'll also pad it in case you drop it (like someone I know).

What a good idea! I am wrapping mine as we speak. That has been a lurking fear of mine that I might drop and break mine. I have been known as "butter fingers" for good reason. Since they wear so little I wonder if a little creativity with wood and epoxy might allow you to take the larger portion and convert it into a comfortable and still useful stump. (I don't EVER want to be called stumpy fingers by the way) As long as the wood parts applied along the length of the stone were thin like tongue depressors, it would not be so bulky as to be clumsy. Wrapping the fabricated wood handle from stone end to wood end with string embedded in epoxy would result in a strong and "grippy" stub. A longer handle on the Norbide might be quite handy as you could rest it on a block while free handing the stone much like working on a wood lathe with cutting tools.

Denis

I don't see why that wouldn't work. Personally, I would prefer to keep it at the length it is though, just for rigidity sake, but that's just me. I typically grip it with both hands while resting them on the mag chuck, or have even used the wheel guard as a rest (paying close attention here) on a T&C grinder. Anymore, I use it most on the jig grinder. It's more convenient there than setting up a diamond with a mag base. Bossman gave me & a couple other guys each one of those diamonds with about a 6" shank on it to use, but I rarely do. I just can't keep it from bouncing some while I try to dress out a wheel.

Denis,

Your pm box is full.I will pm info on payment for dresser when i can. Thanks Jason.