Can I use a table router with grinding bits for stock removal?

pesky_human

pesky_human

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Oct 26, 2008
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I am weighing my options in regards to doing stock removal on some small CPM S30V tools and knives. I have access to a high quality Porter router attached to a ShopCenter 6 in 1 Routing Machine.

This is essentially a solid table router. My father, to whom it belongs, believes that it can be used for stock removal on metal using proper grinding bits. He is a master woodworker and a functional metalworker and welder. Given what I have read about the various procedures for removing steel stock, I am inclined to agree. I would like to know if this is a suitable method for roughing out a blade. I would obviously be hand finishing the blades; this would only be fore rough to intermediate stock removal.

So, I ask the following questions:

1. Has anyone used a tilt-top table router to grind a blade?
2. If so, what are your recommendations as far as bits go?

Thanks for your help, and I look forward to any and all responses. Thanks! ©
 
Me thinks you're barking up the wrong tree. I'm no texactly sure what type bits you want to use..but I think they will either shatter immediately or dull immediatley...perhaps both. Sounds very dangerous
 
I dont think its particularly dangerous. It will just either work, or not. I'm leaning towards not.

John grinding router bits aren't blades or anything. they're basically like spinning files. Heat will be a huge issue for the bit though if it does remove metal quickly enough to be feasible.
 
i also think that steel dust will kill as open motors hate steel dust
 
i can see a piece of steel flying somewhere you dont want it to. i would get the proper equipment and give up on that idea.
 
Perhaps it could work if the router table has a speed control to slow the RPMs. Standard router speed is way too fast.

Sounds dangerous to me.
 
John L said:
Me thinks you're barking up the wrong tree. I'm no texactly sure what type bits you want to use..but I think they will either shatter immediately or dull immediatley...perhaps both. Sounds very dangerous
Click to expand...

I think he means an abrasive bit not a cutter.

That does not mean it would be safe or effective. If it did, it would have similar results to a dremel because of it's small tool.

I used a rotary file type grinding bit at a slow speed in my drill press to clean up the profile of my knife.
 
It has been said but I will say it again WAY TO FAST! It is not a good idea.
Sorry to be a stick in the mudd.
Good luck.
 
A fairly large massive brittle grinding (?) bit spinning at up to 25,000 RPM being engaged with steel makes for some hellatious stresses. I can envision the bit exploding and sending chunks into whatever or whoever is nearby. I have never seen a grinding bit for a router. Nothing larger than a dremmel at least. I'd move over to a sander or files before trying for the Darwin Awards.

Best of luck.
 
If you are impatient, try roughing it on a bench grinder and finishing with files and paper. Bill Moran did his rough grinding on a large emery wheel for many a year to save money on belts. Hell, an angle grinder would probably be a lot safer than a router. You just want to get it close enough to file. On my clip point knves, I take the swedges down about 60 or 70% and then fisnih them up with files. Big file cut farily fast and leave a flat surface. Paper or EDM stones will take out the scratches.
 
I'll be blunt. This is a really dumb idea !

Besides the fact that a router is not made to do this (side load on bearings, speed too high, and such) ,it is highly dangerous, and the rotary bits are not milling machine cutters. I understand that thinking out of the box is a good thing, but this thought could send you to Doc-in-the-Box, as well as mess up some nice equipment.

Stacy

Edited to say;
I am not calling the poster dumb, just the idea.
 
Last edited:
Stacy really hit it. Its a router and not a milling machine and you are asking it to preform like one. Look at the stiff rigid stetups on the spindles of milling machines and then look at your router. Jim
 
you'd be almost safer (a lot) by using an angle grinder! Smells like crap! but would remove metal
 
I thought of trying this along time ago but decided not to do it.
I have heard of knife makers using routers with carbide end mills and various shaped cutters in them to do decorative file work on their blades.
If your Father is an avid wood worker I'm sure he has a couple good belt sanders in his shop you could use to grind the blades. Grinding blades on a belt sander is not as difficult as folks think it is. You can even make yourself some guides to help you keep the grind lines even on the blade.
I'm into wood working right now and want to get back into knife making so I'm going to build myself a Rob Frink KMG style 2 by 72" belt grinder and use 3/4" plywood for all the parts I can. I'll laminate 2 pieces of it together to get 1 1/2" thickness which will be more than strong enough and should last me till I can afford to buy one of Rob's jewels! :)
Whew, didn't mean to rattle on this much!!!
The moral to the story is- you probably shouldn't mess with steel and routers at the same time! :D
 
Great question! Nice to see some out of the box thinking. I believe the RPM's on the router would be way too high for an abrasive type bit. I'd be afraid of them exploding with a sharp knock at full speed. I've seen video of Geno Osborn using a router and carbide bit mounted to a router table and it worked fine. Carbide is carbide whether it is in a milling machine or router. I think there using a router this way is really dangerous. When you mill metal with a carbide cutter, you bolt it down to a milling table. Holding it by hand and then pushing it into a cutter is just asking for trouble.
 
A 6" bench grinder turning at 3,600 RPM is going the same speed as a 5/8" stone turning in a router at 36,000. Same SFM. It isn't too fast unless your diameter is too large.

Tracy is sort of correct that carbide is carbide in that everybody is pretty much using tungsten carbide. But the carbide used in wood cutting tools is harder because they use less binder. So it wears better, but is too fragile to be used in steel. And the cutting geometry in good wood cutting tools is different than the geometry used in metal cutting tools. Specifically, there is usually more chip clearance, at the expense of strength. Carbide in a router in steel is not a good idea because only a very small cutter would be appropriate at these speeds (like 1/32"), and small cutters do not tolerate the wild runout of wood tools well. The magic number for SFM with carbide and steel is seldom more than 250 SFM, and frequently is less than 100 SFM in tool steels.

A properly sized abrasive bit, in a controlled setup, should be able to grind with a router. Abrasive bits in steel are less prone to dig in or self feed than a fluted cutter in wood, so I tend to think it would be just as easily controlled/safe.

A grinder could work. A fluted cutter will not.

There will be two problems. One is the conductive dust as already mentioned. The other is runout and an imprecise setup. The heaviest cut you would want to attempt would only be about .001" per pass, similar to what would be used on a small surface grinder, Jig grinder, or toolpost grinder. The problem is the runout on a router spindle is more than that, so even if you dress the stone in the spindle, you may have problems maintaining an optimal amount of engagement without a lot of hopping.

If you're thinking about just holding the blade in your hands up against the stone, that isn't very controlled, and I think Richard has made an accurate prediction. I'm not sure that would be very safe. It would be better to have the blade clamped down and hold the router so nobody gets stabbed by a flying blade.

I'll point out that a risky procedure with wood has more serious consequences when it is a steel blade being worked on.
 
I did used a Craftsman Router, I took off the lower piece that does the adjustment, and using a bit that held a 3" cut-off wheel, using it to rough out the profile of blade. It was hand held and it was very dangerous and throws alot of sparks. I did this a few time and then gave it up.
 
I've tryed it with a hand held craftsman router, it was a bad idea and a lesson learned, the steel may not get up to 1850 deg or better but it does harden enough that after the first pass the bit will not touch it. But I tried to make a 2X72" grinder using a lawnmower tire from the lumber yard, who would of ever thought they are not ballanced to run at 1720 rpm's? My lesson learned is if the funds are not there dig ditches or what ever it takes for the extra money and get good and proper equiptment. You will make useable knives and save your life.
 
Thanks for all the feedback. First off, I am asking and researching in order to determine if it is viable and safe. If I were to try using a power tool on steel without doing so, then it would be a dumb idea. Giving that I am asking, I think it's fair to just call it an idea.

Given the feedback, this is not a route that I will go. It will be handy to have the router table around for wood operations. :) At any rate, preventing and/or mitigating injuries of a beginning knifemaker has got to be one of the most noble and important goals of this well-traveled forum. Thanks again to all of you who took the time to respond in an honest and informative manner.

It looks like I am going to be saving up for a belt grinder. I keep wondering what magic is being done in order to justify a very simple machine that costs $2000+.

...and the research continues. ©
 
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