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Rex Krueger
Rex Krueger

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Behind the Scenes: Grinders for the Wood Shop

Friends:

I'm in the middle of a big video on grinders for the wood shop. I see a LOT of misinformation about grinding tools. People say you can't do it on a high-speed grinder. They say you'll ruin your tools. They see you NEED slow-speed, or water-cooled, or CBM wheels.

Hogwash!

We're going to get down to ground truth on grinders for chisels and plane irons. Along the way, we're also going to review the most affordable grinders and accessories on Amazon.

Since you are my most trusted audience, it's only right for you to see what I'm up to. Have a look at this short, behind-the-scenes video and let me know who YOU want me to cover. It's going to be a couple of weeks before it's all done, so your input will be very valuable.

Comment below!

--Rex

Behind the Scenes: Grinders for the Wood Shop

Comments

Sorry it took so long to reply. I've been without for a month. There's a German guy who has a video on sharpening plane blades with a hand grinder. https://youtu.be/L7bqHpvcZTw?si=-jzGX0AVmYLDRSsb He made a very sturdy rest out of birch plywood. I have a copy of his plans. If you would like them, let me know. I can email them to you.

Michael Bennett

Hi John, for me it can be quite beneficial to have the edge a little bit hollow. I do the day to day sharpening by hand which becomes much faster since I don't have to grind the whole beveled surface. Then after a couple of times (probably more like 15 times or so) I go back to the grinder (6 inch) and "hollow out" my edge again. At the same time I couldn't notice any disadvantages. Of course it is not my idea I think I got it from Cosman. So to answer your question - I don't think it should be mitigated.

Maximilian Harth

I have used grinders to get the correct angle on my plane blades but it always leaves the edge slightly concave due to the curve of the wheel. Is there anyway to mitigate this?

John K. Mackenzie

1) I have a couple of the aluminum tool rests that just will not fully lock in as set. Any pressure moves their platform or pivot point. I’ve improved it by adding lock washers, but it’s still not as stable as I would like. Maybe you could find a better solution. 2) The platform on these tool rests is too small and the surface is uneven. Maybe you could come up with a solution for improving it. Thanks, Rex.

Robert Judy

Biting nails!

Bradley Barth

Looking forward to this one

John M

Is James Wright doing the spreadsheets for you?

Chris St. Cyr

Looking forward to this video coming out. I have a mini grinder (about a 4 1/2" wheel size) but I can't find replacement wheel or wire wheels that size. Also, I have to make a wooden tool rest, as the fitted one is not adjustable, and about an inch wide.

Bat

- Replacing the stock gray (SiC?) wheel with a friable white (AlOx) ($20-25 for Norton; not the 3X). Worthwhile or thoughts otherwise? - Rebalancing/dressing a wheel every time it's installed. Been told by someone who seemed to know that it was standard practice (for pro metal/machine shops). - Wearing respirator/breathing PPE. I feel like I should always do this, but rarely do. Does SiC vs AlOx matter? (Silicosis vs ???). Glasses are easy; I'm more likely to forget to take them off than put them on. - Another vote for how to set and check angle for tool rest. Made a stick with 25° and 30° ends reference per Schwarz but haven't felt I've used it quite correctly. (This is where thickness of the reference can matter.) Recently saw someone using scrap and hand-turning the wheel to see where it hits, which is better but still seems like it could be more accurate. - Tips for getting the wingnut for the tool rest tight and loose. Forged an old end wrench into a tool for this, although it occurs to me a regular hex nut and wrench would be more straightforward. Added a split lock washer but I still have to tighten it pretty hard to keep it still. I have other things that are probably out of scope for this video (like using a variable speed drill with MDF wheels and compound for honing) which I'll probably post about on the forum at some point.

Wil Cooley

I wouldn't use a bench grinder for kitchen knives, aside from doing a major restoration. Because they have such a small bevel, it's not all that much work to do by hand and can be done reasonably accurately with a guided system like those sold by Lansky. I'm sure Rex'll talk about this, but my understanding is that you grind bevels, not edges -- the steel at the edge is too thin to dissipate heat quickly enough. Water, slow speed, CBN, etc are needed for grinding edges. (I hear woodturners often go straight from grinder to work, so many of these people need/want to grind the edge.)

Wil Cooley

I have 6" that I used a little before buying an electric. It worked for grinding plane iron bevels but a tool rest and jig is paramount -- you only have one free hand and even that isn't steady due to turning the handle with the other. Now I keep it in my smithy for deburring and small jobs that I don't need to deal with electric tools for. I have another 3" but haven't found a great use for it. I should also add that you can easily overheat steel with a manual grinder too.

Wil Cooley

I've not had a bench grinder before, so any info is welcome tbh. How to choose and then use safely would be the most important things for me tho.

Jim

Rex, this is probably too late for submission, but I would like you to cover types of wheels, grits, and how to read abrasive wheel codes that reference what they can be used for and how to use them. Maybe the later is more viable in a metal shop rather than a wood shop but it would be nice to have a clue.

Tom Broome

I'm reading "An Edge in the Kitchen" so will ask, can kitchen knives be sharpened on a grinder as well? Do different steels (like X50CrMoV15) need different tools to grind than others (X50Cr15)?

George McQuary

Hi Rex, I have an old grinder that doesn't have visible brand or any other info. A video of how to make it more functional and set it up would be amazing

Thomas Andersen

An excellent point. I would say: as far from the bench as you can get it. They are kind of dirty, so away from the main work area.

Rex Krueger

The rest is pretty much half of the machine, so I'll get into it.

Rex Krueger

Excellent questions. The answer is coarser stones and I'll cover my reasoning. As to the hand-crank grinders, I don't have one, so I better leave that to people who know better.

Rex Krueger

That's a complicated question and the short answer is: you use a simple jig to set the angle and you check it as the wheel shrinks over time. Grinding a tool gives you a wide margin of error and as long as you check that angle against a simple wooden jig, your angle will be good *enough.*

Rex Krueger

Yes, we'll get into the aftermarket tool-rests. An essential aspect of the whole thing.

Rex Krueger

I think I'll avoid turning tools, since that's a whole other world. But I do agree with everything you said!

Rex Krueger

Ah, good point. We'll get into that.

Rex Krueger

You're totally right about the difference between the alloys, but you're also falling into a common misconception that grinders pose a real risk of drawing the temper on plain, high carbon blades. The risk is actually very small and a little spot of drawn temper will have no effect on the tool in most cases. I'll get into this. I might even burn a tool on purpose to show how it still works.

Rex Krueger

It's not hard! Pick an inexpenisve 6" model. Buy or make a tool rest. That's really all there is to it....but I'm going to cover it in more detail in the weeks ahead.

Rex Krueger

I agree that CBN is the way for turning tools, but I can't get into turning in this video. I'm going to keep it focused on plane irons and chisels and I'm going to tell people they should save their money and use inexpensive gray wheels for those uses.

Rex Krueger

Yes, the tool should turn toward the wheel. It's pretty hard to get a "catch". The wheel is just too hard for the tool to dig in. 4" is very small. Probably too small. I would get an 8" grinder. I think the cost is justified.

Rex Krueger

I think used is a great idea for folks who have a little mechanical know-how and can fix common issues like a frayed cord. May people who need a grinder are beginners and for them, I think new makes more sense. The plug will be grounded. The wheels will be new. Easy. Safe.

Rex Krueger

You make a good point: some folks are going to confuse sanders and grinders. I need to make sure folks understand the difference.

Rex Krueger

I'm pretty sure you can find spacers specifically for that purpose. When I bought my CBN wheels for my turning grinder, I also bought washers intended to fix that spacing issue. They were right on the same page.

Rex Krueger

I think this is fine to do for buffing wheels if you buy a kit made for the purpose. As to a grinding wheel....eh. I'm sure you can do it, but the wheel wouldn't be covered by the protective shroud. If the wheel explodes (which it totally can) you can be seriously injured. This is probably a bad idea.

Rex Krueger

Yes to safety glasses, maybe no to gloves. I don't use them. Anything cloth can get sucked into the grinder and get caught, which is very dangerous. Keeping your hand away from the wheel isn't very hard. I don't think I've ever touched the grinding wheel with my skin. I have touched a wire wheel and it's the equivalent of a rug-burn. Painful, but minor.

Rex Krueger

I'm certain you didn't harm any of those blades at the grinder. Only thinner blades are at risk and it's easy to manage. Rest easy. You're already quit experienced and hopefully my video will cover the rest.

Rex Krueger

This has happened to me many times. One of your wheels might be bad, but more likely, the wheel has the wrong diameter bore and needs a small bushing to run true. These are often included in the package but not clearly marked and it's easy to throw them away. (Ask me how I know.)

Rex Krueger

Don't buy a Tormek! I'm totally convinced those things are a scam. (At least for any kind of woodworking I've ever done.) If you're turning on a powered lathe with modern turning tools, you need a grinder. For turning, I suggest an 8-inch grinder with "white" wheels. These are designed for turning tools and work really well.

Rex Krueger

They do, but it's easy to measure yours. They're pretty standard. Good point!

Rex Krueger

Don't fear the grinder....but do respect it.

Rex Krueger

This is the first I've heard of a deburring wheel! I'll need to look at those.

Rex Krueger

All excellent points. I cannot recommend using a 6-inch grinder for turning tools. It's possible, but the radius and composition of the wheels makes it less than ideal. For turning, I suggest an 8-inch grinder with "white" wheels. These are designed for turning tools and work really well. As to making your own Wolverine jig, you need to do a bit of welding to make mine and honestly, I think most folks should just buy the Wolverine. I have one now and it's totally worth the money.

Rex Krueger

It's certainly a legitimate way to do it! Belt-sanders are probably under-appreciated as grinding tools.

Rex Krueger

A good point, I never use the grinder for camber unless it's my scrub/fore. For everything else, I camber on the stones. I will be sure to cover this.

Rex Krueger

Sorry trying to sound like I know what I’m talking about. An OBMC is an oval bolstered mortise chisel. I don’t like the term “pig sticker”. Sounds too violent

joseph severson

You know, I don't think the thickness of the tool has any bearing on the angle, but that's just off the top of my head. I'll be sure to think about this as I work. I might need to cover this.

Rex Krueger

Excellent. The tool rest is paramount, so I'll cover it thoroughly.

Rex Krueger

A worthwhile topic. I might have to do a separate video on that.

Rex Krueger

I think I'll cover all of that, except I don't know what an OBMC is! The internet is alphabet soup!

Rex Krueger

I'm sure it is the same. I just bought the cheap one. I'm quite sure it's fine, even though it's still in the box.

Rex Krueger

Perfect. These are topics that I am absolutely going to cover!

Rex Krueger

That's an excellent topic and I will cover it!

Rex Krueger

For light grinding of tools, the dust isn't too bad, but I agree that outside is the place for grinding if you don't have a shop.

Rex Krueger

We will absolutely cover that!

Rex Krueger

Well, that's a great topic! You can't use a grinder to get a high polish, especially on wood, so that's easy to answer. You might be thinking of a buffer and while I do own one of these, it's really a specialist tool that you don't need. I don't use mine very often. You can mount buffing wheels on a grinder, but you really want a dedicated machine to keep grinding dust out of your buffing jobs.

Rex Krueger

Hm. I'm not sure I actually know the answer to that one. I think you should post that on the forum to get more opinions!

Rex Krueger

Hi Rex -- How about where a grinder should be placed in a shop (or maybe where it shouldn't be placed). Thanks

Frank-L

Glad to see the look at tool rests. I'm good for grinders but a good tool rest and tips to set it up would be great.

Duncan Haigh

I have 2 suggestions. 1. There is a debate about using coarser and finer stones - speed, heat buildup, etc. 2. You find an old hand grinder at a flea market. Do you keep walking or not? What should a noob look for?

Michael Bennett

My overthink-y question on tool rests and grinding angle is always...well...angle compared to...what? Wouldn't the position of the rest relative to the diameter of the wheel where it is parallel to the floor really be _the_ spot? and point "above" or "below" that would need some sort of correction? More or less depending on the size of the wheel....makes less difference the bigger the wheel is?

Jon Linna

My 8 inch WEN grinder, under $100, works wonderfully. I did get fancy CBN wheels eventually but even those will burn on a high speed grinder if you're careless. Proper technique is not hard to learn. I love the CBN wheels more for never needing dressing, not sparking as much, and not having to worry about explosions if there's a crack in one of them... My main issue is with tool rests. I just can't find one I like and setting them up to the proper angles seems fiddly and difficult. Worst part of working with the grinder IMO. Would appreciate focus on that.

Brian Stevenson

This is something I needed a decade ago! About 3 years ago, I bought my 2nd grinder. While I agree that a CBN wheel is not necessary, I would save for that over many other things! I use the Wolverine sharpening system for my lathe tools, but have seen “Glen and Lisa” build that jig out of wood! That is honestly easy and deserves to be covered. I quickly learned with my lathe tools that having a jig so that an edge can quickly be touched up saves so much time. And sharp tools cut so much better.

Michael Coolidge

Tips on squaring up the wheel after it has been rounded over from years of amateur use.

Thomas Harm

I recommend a full face shield when using a grinder They don’t cost that much and they provide better protection. That is what we use in the construction sector while fabricating pipe spools.

Richard C von Brecht

I think it would be useful to make the distinction between high carbon steel and high speed steel (HSS). Heating up high carbon steel on the grinder will cause it to lose its hardness and degrade the usefulness of the tool. High speed steel is much more tolerant of heating - you can bring some color up when you're grinding without too much ill effect.

Brian Taylor

This might be adding too much but the used market for grinders around here is very healthy, you can get really good quality brands for a fraction of the new price, and they often come with other wheels and accessories. I don’t know if I got lucky with my used grinder or if there are common issues to look out for? Any long term maintenance that needs to be planned for?

Henry Singleton

I’m working on a boat which often means cleaning fouled surfaces, and there’s a lot of it. I’m retired and in theory have plenty of time. But if I do this by hand I’ll be dead before we sail away. Do I know have a lot of these 12 volt makita compatible sanders and grinders. Many I have Velcro type pads in for speed of changing. Using the old style sanding board won’t work for me anymore. So while I’m working on some project, I often spend a couple of minutes taking the edge off my old rough chisels and they are quickly back to sharp enough to work well on our boat. This is a great idea Rex. Btw I tend to dial back the speed to the slowest option. That way I don’t think I’m getting the blades too hot to harm the metal. I hope this helps Rex. I think you’re on the right path. These tools are cheap. Talking about cheap, these sanding discs always tend to wear along the edges. When a sanding disc is no longer viable I put it aside until I have a few like that and cut them down for reuse. I use a multi tool for removing old pieces of timber (often held on with sikaflex) . It has a small triangular Velcro type pad for detail sanding in corners etc. My old discs become triangles and get a second life before going into the bin. E use a lot so every one not tossed before it’s time I’d good for me and good for the environment.

Col Rodrick

They make a pretty horrible mess, honestly. They throw iron/steel filings all over - all that metal you're removing has to go somewhere, after all. And personally I find metal filings a lot more irritating to deal with than sawdust. Any time I have to use it for anything significant I lug it outside or to the garage and clamp it down to use it (to a Workmate-type folding bench, or to the deck, or whatever). You can clean up iron / steel filings indoors, but to me it's not remotely worth it.

Tim Kaiser

Brilliant! I'm literally working on setting up my grinder right now. I "bought in" to the idea that I needed a CBN wheel, and picked up the same 180 grit one mentioned by Hal Songer in his comment like 15 minutes ago. It slips on the shaft nicely, but the shaft is way too long, so now I have to figure out if I need some regular washers, or a special bushing, to take up that extra space, or what. Also - as far as tool rests, as a cheapskate, I couldn't stomach the price most of the decent looking aftermarket ones were. But this guy seemed to have a really clever system one can build from scraps for basically no money, which is what I'm building: https://www.youtube.com/watch?v=NWz64eeVbwQ&t=397s

Tim Kaiser

Are you psychic or something? I've been trying to muddle my way through picking out a bench grinder.

Richard Lightfoot

if you are touching on CBN wheels as an option, is there a difference between the cheap ones and the more expensive ones? I picked up an 8" 180 grit CBN off of Amazon for $65 and it seems to work great on my turning tools. It's got some wobble so I have ordered a set of spherical washers to try to correct that. I also found that the CBN sits too close to my guard so had to make a spacer from a bushing to have it centered in the guard housing. Any other gotchas about going to a CBN and whether aluminum or steel have any benefits other than inertia would be helpful.

Hal Songer

Brilliant idea, Rex. :) I would like to know how I could sharpen my bowl gauge. My questions: - Can I sharpen a large gauge on a small diameter wheel (~4")? - Is it OK if the wheel turns towards the edge, not away from it? I got responses from various sales people like "Meh, it is OK", "Exactly, this is how it should work" but my gutfeel is "no, it is dangerous if the wheel catches the edge of the blade". Can you clarify it, please?

Csongor Halmai

I would like a discussion of necessary safety equipment like goggles and protective gloves. At the moment I don't want a grinder and would also like a mention of alternatives to a grinder.

Madeleine Yeh

I have an old lathe, and I've heard some people repurpose their old lathes to hold a wire wheel or a buffing wheel (I don't think I've seen anyone do a grinding wheel, as it seems like you'd increase the danger and would have a hard time pushing against a grinding wheel stabilized by a lathe). Maybe mention the relative safety and/or practicality considerations of doing this.

Kyle Painter

Very exciting! I'm quite keen to find out exactly what I should and should not be sharpening or removing on the grinding wheel. I have sharpened axe heads, machetes, and lawnmower blades, and did not realize until possibly too late that I had introduced a fair amount of heat into the metal. I also have been freehanding all of that, so I'm interested in tool rest recommendations/setup/best practices. Eagerly looking forward to hearing about the myths, amelioration, and proper usage.

Chris Smith

My grinder vibrates like ca-razy. I don't know if that's normal and if not how to fix it. Also, safe ways to shim a thinner wire wheel would be useful. These two things may be very related...

Kenneth Carlile

I'm interested, in part because I'm starting to get into wood turning (someone gifted me a Mini Lathe) and I get the impression that turning without having a grinder or other powered sharpening system is going to be a pain in the proverbial. Coming as well from a carving background, people are often talking about things like the Tormek or the Robert Sorby Pro-Edge system, but I don't have the budget for that - so a relatively cheap 6" or 8" Grinder is probably where I'm heading. What pitfalls to avoid is probably the thing - how to avoid doing damage!

Rob Weir

Replacement wheels, how to choose and mount them. The grinders may be 6", but the arbors (axle diameters?) vary a lot.

Peter Svedman

I was afraid of my last grinder so looking forward to this!

Gerald Eddy

I have plenty to say about grinders but I’m not sure how useful it is. I’m on my third Harbor Freight grinder but that’s over thirty years and one was stolen by my son. They are a little underpowered, which is a plus in that it forces you to go slow. My dad made one out of an old refrigerator motor. That had too much power. I mounted my grinder on a thick sheet of plywood and clamp it to my work bench as needed. It saves space for other things. I have that after market tool rest you showed. It’s slightly better than no tool rest. I got the best results when I mounted it backwards? I hope your video has some good techniques for using it. Taking the wheels off can be tricky. Unlike hand grinders there is no wheel lock. Showing people how to do that without going crazy would be useful. (You need two wrenches) Besides a wire wheel, I use a 180 grit deburring wheel for restoring wood planes and chisels. They’re not necessary but are convenient for getting that last bit of grime removed.

Richard C von Brecht

Perfectly time for me as I investigate getting into wood turning. I would appreciate your thoughts on dressing lathe tools on a high speed 6" grinder. Methods you use. Additionally I recently read on the forum you built your own grinding system a la wolverine type. Covering that either here or in another video would be highly appreciated. Thanks for all your do. I've said it meant times and mean it sincerely each time.

GFHWoodWerks (Gregory)

(Sorry, I commented on the video) Before I got a 6" grinder, I used a battery-powered (Ryobi) belt sander with an 80 or 100 grit belt to establish a bevel and a decent camber. I used an inexpensive honing guide that rested on the end of the sander, with the sander inverted in my vise. I think the battery-powered belt sander is a bit slower than a plug-in belt sander and that made it easier to use, and less likely to burn the steel.

Fred Wolsey

A blade of any kind will be hardened by heating it until it is bright cherry red, quenching it in oil or water, depending on the steel, then "drawing" or tempering by heating it to a light straw colour but not more than a pale blue colour. This softens it a bit, and makes it more ductile (less brittle). In both case while the chemistry of the steel remains unchanged, the structure of the steel is very different. Each colour change corresponds to a change in structure.. (That's kind of simplified, but close enough). If you add too much heat after the temper, it will soften too much and be very ductile to the point where it will not hold an edge for any length of time (The edge may simply curl like the burr when you sharpen.)

Fred Wolsey

Radius on plane irons. Popsicle stick angle checks. Time on stone vs. temper of blade.

Russell Nowell

Maybe touch on setting the angle of the tool rest, vs. the thickness of the tool/iron being ground.

Monte Milanuk

Once I get my irons and chisels set, I rarely have to come back to the grinding wheel. I think the trick is to stay on top of the sharpening; 1) it makes work easer, 2) you catch the small knicks early so you can take them out on the stone. I think the most challenging operation of the grinder for me is putting a radius on the planing irons, and then maintaing that radius though all the shapening on the stones.

David A Larrabee

Well need a jig of course. One that can be adapted to a variety of low end and better grinders. To replace or improve the existing tool rest and get that perfect angle. Looking forward to it my friend

Greg Preston

Grinding a scrub plane iron.

Jon Rost

I would really appreciate it if you could discuss re-establishing and sharpening mortise chisels specifically the OBMC. If you have time I also recently purchased a Stanley 750 at an estate sale but the bevel is convex. Can I address this on the grinder as well? Thanks for all you do Rex. You da man! By the way I only have a Harbor Freight high speed 6” grinder with the aluminum aftermarket base you showed in this video. Sorry, one more question how high on the wheel should the base align?

joseph severson

Just got a new grinder and am about to build a stand for it so really excited for this as well. Christopher Schwarz basically had the same recommendation about not worrying about slow speed, etc. which is what led me what I think is the same Dewalt you have pictured :)

Anthony Checkas

Perfect timing: I have a hand tool only shop and am looking to buy a grinder to put a Primary bevel on my irons plus a wire wheel to help renovate old tools. I would like to know about minimum HP required, size a width of grinding wheels, type of grinding wheel. Plus do I need an after market tool rest? Plus brands that don't suck. Thanks, David

David Egerton-Warburton

I would love to hear a little actual science/metalworking knowledge about grinding too hot "ruining the temper" of the blade. I know you've basically said,"Trust me, this won't ruin the temper as long as you repeatedly dip it in water, and grind off the discolored parts of the blade. " However I would love to hear a longer explanation/reasoning for this, as I'm sure it would be helpful and interesting to someone with less knowledge of metalworking and blade steel such as myself.

Andres Hernandez

How much clean up they need? My 'shop' is a spare bedroom and I don't want to make a lot of dust in the house, if I can prevent it. Hence also handtools, chips & curls are not very dusty.

Wouter Engels

If you have any tips for establishing/reestablishing a bevel angle on plane irons/chisels. That would be great. I can touch up an existing angle ok, but useless doing a new one on the grinder.

Jason Brooks

Hey Rex, using the grinder to achieve a high polish on wood or metal has been a mystery to me. I've followed advice online but have never got that perfect shine. Thanks 👍👊

Lee Nightingale

I bought a really old grinder off Facebook, multi speed. It doesn’t seem like it’s terribly accurate. So I’d be interested to know if it’s worth trying to use, and how to tell if I should reinvest in something else. Thanks Rex!

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