Perspectives on different methods of planar knife sharpening

[Random Orbital Bob]

I got somewhat sick and tired of the time and cost of sending planar knives to a service so I decided to try self sufficiency. I bought Tormek's plane sharpening jig. It works but there's no easy ride I can tell you. Also if you have a ding...not good...that's a lot of grinding. (And I have the carbide blackstone too which is marketed for HSS and exotics).

Has anyone used those hand held honers that you just run up and down the blade in situ? I cant believe they're anything but gimmick but would still be interested to hear any experience.

More importantly, if folks don't use a service...what method do you use and does it work...time taken etc.

Jointing or flattening rough sawn timber is a joy with freshly sharpened knives but that HSS doesn't shift easily...anything that keeps it in house but makes it easier is worth reviewing in my view.

Thanks

 

[longinthetooth]

I can't imagine any DIY-grade device or jig that'll either cut quickly or give a straight grind. After all, you need a straight grind on a planer knife, and this implies a grinding machine of a certain rigidity. So I'd bite the bullet & keep sending the work out. Surely there you've got a local tool service firm? Or at least a collection agent for one? The actual grinding's cheap enough if there's no postage involved.

 

[Jacob]

There's a dead simple jig you can knock up - basically two saw kerfs in a block so you do two blades at a time with each registering off the other. Either on stones or wet n dry. It works fine. I use it a lot but then send them off every now and then.
NB you don't necessarily have to remove a whole ding - just offset the blades a touch so that one will cut where the other is dinged.
Steve Maskery did a thread a bit back.
I'll find a photo if I can.

 

[custard]

On my previous P/T I honed and sometimes back bevelled planer knives in situ to deal with tear out, I followed the process given by David Charlesworth in one of his books and it worked a treat. I now use a P/T with disposable knives and (so far at least!) haven't had any tear out problems, but because changing knives is a two minute job I'm tending to be much more diligent about maintaining sharp and accurately set up knives.

By the way, the traditional system of setting up knives, measuring how far the knives move a wooden straight edge, is okay and is what I did for years, but using something like this gets the cutting circle of each knife within one thou right across the planing table, which means all the knives are sharing the work!

http://oneway.ca/workshop/multi-gauge.htm

 

[Harbo]

That's quite easy to replicate with an Engineers stand and dial gauge?


Rod

 

[Random Orbital Bob]

I have the oneway multijig already...its absolutely superb. This isn't about setup...its purely to do with sharpening. The Tormek jig isn't cheap either and it does work...just a tad time consuming and fiddly to setup. In terms of a straight grind (to maintain knife balance) its engineered to solve that problem automatically. In fact its brilliantly designed...its simply that HSS is a pig to grind ...period.
When I first joined this forum there was a long series of threads about knife setup (with Steve Maskery deeply involved) and it was after that I went ahead and bought the oneway. I hated that wooden batten advance method because its so "blind". With the Oneway I have complete visual control over the actual empirical height to the thou and can experiment with varying it if necessary. That way I can be confident that any given setup is the specific cause of a given result.

Like the idea of the two saw kerf jig Jacob..might give that a try. Also am familiar with the "moving the dings out of alignment practice". Again...the aim here was to research what methods people are using for home based knife sharpening to see if I can improve the way I do it.

Thanks to all so far for posting. Please keep them coming...there must be dozens more surely??

 

[marcros]

Bob,

Did you get your Oneway over here, or import it?

 

[longinthetooth]

There's a dead simple jig you can knock up - basically two saw kerfs in a block so you do two blades at a time with each registering off the other. Either on stones or wet n dry. It works fine. I use it a lot but then send them off every now and then.

I think I can imagine what you're on about Jacob, an advance on my kerfed block with just one slot. Good idea. But that's honing - the problem is grinding. I still can't imagine how anything that fits on a Tormek can be rigid enough to give a straight grind.

 

[Random Orbital Bob]

I had a bit of a saga on that...called Canada...they put me on to Germany (Master European distributor) who in turn put me on to Toolpost in Oxford whereupon they were out of stock. So I hung on for two weeks and got it. £95 or thereabouts so not cheap but planar knife setup developed into an obsession with me for no reason I can possibly fathom.

That Oneway multigauge has totally revolutionised its accuracy. Its also great for setting fences square because you do it hands free. Also for a myriad other fine adjustment tasks round the workshop including setting infeed to outfeed zeroing coplanar as it reaches all the way over the block when referenced on the outfeed side. Plus setting tablesaw blade/fence alignment etc.

Its really heavy duty steel and the little dial foot comes with the fleshy wide foot and not just the pin head style that always slips off the planar knife edge...they've thought of everything....I really highly recommend them.

 

[Random Orbital Bob]

I still can't imagine how anything that fits on a Tormek can be rigid enough to give a straight grind.

The tormek jig is called the svh-320 and its basically a sliding carriage with a rigid steel back plate. The knife is set into this and the operator moves it across the wheel. It does give a perfectly straight grind. Frankly it delivers a better edge than both the factory and any sharpening service I've ever used. The problem is time....HSS glazes the grinding wheel very quickly because its so dam hard. So you're forever re-grading the wheel to get it cutting again. But the engineering behind the jig is very clever......and the quality excellent. Its the material, not the jig.

You can see it in operation on youtube to validate the rigidity.

 

[Random Orbital Bob]

actually......another related question....what are folks typically paying per 12" planar knife for a service?

 

[Jacob]

There's a dead simple jig you can knock up - basically two saw kerfs in a block so you do two blades at a time with each registering off the other. Either on stones or wet n dry. It works fine. I use it a lot but then send them off every now and then.

I think I can imagine what you're on about Jacob, an advance on my kerfed block with just one slot. Good idea. But that's honing - the problem is grinding. I still can't imagine how anything that fits on a Tormek can be rigid enough to give a straight grind.

This is the idea. This one for 3" hand planer. (Ignore the knackered blades there's a better pair in the machine!)
Instead make it from 2x2" the length of the blade with 2 saw kerfs at the right angle (120º) to give 30º at the edge (if 30º is what you want).
Grind on coarse grit, hone on fine. The big advantage compared to most jigs is that only the blades touch the stone.

 

[SurreyHills]

I use the jig that Steve Maskery has shown on here. It's easy to make and is good for touching up dull blades. But if I needed to take a ding out then I would send my blades off to be "professionally" sharpened.

 

[custard]

I had a bit of a saga on that...called Canada...they put me on to Germany (Master European distributor) who in turn put me on to Toolpost in Oxford whereupon they were out of stock. So I hung on for two weeks and got it. £95 or thereabouts so not cheap but planar knife setup developed into an obsession with me for no reason I can possibly fathom.

That Oneway multigauge has totally revolutionised its accuracy. Its also great for setting fences square because you do it hands free. Also for a myriad other fine adjustment tasks round the workshop including setting infeed to outfeed zeroing coplanar as it reaches all the way over the block when referenced on the outfeed side. Plus setting tablesaw blade/fence alignment etc.

Its really heavy duty steel and the little dial foot comes with the fleshy wide foot and not just the pin head style that always slips off the planar knife edge...they've thought of everything....I really highly recommend them.

Ouch, I picked up a Oneway a couple of years ago when I was working in the US, it cost about fifty quid!

 

[JakeS]

Grind on coarse grit

Got any tips on making that take less than a million years? I've been steadily re-bevelling an ancient plane iron by hand during downtime using 80-grit paper (because I'm rubbish on a grinding wheel anyway) and it's taking... a long while. And I have another one to do after this that some sod put a rounded bevel on! :twisted: (Seriously, it needs regrinding 'cause there's a significant nick in the blade.)

(Although now is as good a time as any to thank you for mentioning that magnet-in-cling-film trick, that helps a lot!)

 

[powertools]

Well I have to say I am happy to own a 30 year old Kity universal machine that includes a 535 planer that comes with a grinding jig that fits on the side and I have never had cause to send the blades away for sharpening or had to purchase any expensive system to achieve a sharp edge.


NB you don't necessarily have to remove a whole ding - just offset the blades a touch so that one will cut where the other is dinged.

Thanks for that simple tip Jacob I have to say I have never thought of that and will do that in future.

 

[Steve Maskery]

This is my approach. Yes it's presented as Honing, but actually, if you start with coarse-enough emery cloth stretched over your flattest surface, there is no reason why you could not grind this way.
http://www.youtube.com/watch?v=xIBKp9_hWLo
Personally, I think it is better than a Tormek or equivalent. Using a stone like that does not even out any divergence from linearity, if I understand it correctly. It simply sharpens the line that exists. Rubbing on a flat surface gives you the straight edge that you need.
S

 

[Giff]

Bob you are probably too far down the line with your sharpening kit now but Cutting Solutions do replacement turnblades with holders and once set up takes minutes to replace knives on the planer. Geoff

 

[Random Orbital Bob]

I will investigate turnblades...that intrigues me....no idea of the cost yet though.

Steve - the Tormek jig does account for any non linearity because the back of the knife is referenced against a linear stop at the back of the jig. Thus once grinding is finished the edge is exactly parallel to the referenced edge (which will be a factory edge).

Again...the problem is the time it takes to grind HSS...its just a bellyache because the stone keeps glazing and therefore stops cutting. I'm resolved to try a diamond dresser to reactivate the stone quickly. That may help. Once the grinding is done with the Tormek its exceptionally sharp....far sharper than I've ever experienced with so called "professional" sharpening. It's just a pain to do it that's all.

 

[Steve Maskery]

I didn't realise that, thanks.
The one I saw wasn't a Tormek, but I thought it was identical in operation. Obviously not.
S