A Couple of Blade Grinding Jigs

[derekcohen]

1. Flattening the back of a blade.

I always find flattening the back of a back a real pain in the whatsit. This includes both chisel and plane blades … blades that are either rounded or pitted. My strategy to date has been sand paper on glass.

I had in mind a blade that I wanted to use in my Spiers infill smoother. It had potential but was pitted on the back near the edge of the blade.

What I have now done is to basically create a surface grinder out of the disk sander section of my belt sander combo.

Sanding disks are all easily and quickly swapped over since they are Velcro backed. The sequence begins with 120 grit, moving to 240, 320, 600 (25 microns) and 1200 (9 microns). This is then polished on a leather strop disk with Veritas green rouge (.5 microns).

The idea for using the disk sander only gelled when it occurred to me that I could use the magnetic base of my Dial Gauge to hold blades securely against a fast spinning disk. Note that the right side of the sander is used so that the disks do not turn into the blade (since the 600 and 1200 could tear).

<center> <div><img src="http://i13.photobucket.com/albums/a262/Derek50/Articles/Flattening%20backs%20of%20blades/Bladerestoration5.jpg" border="0" alt="" /> <br /></center>

<center> <div><img src="http://i13.photobucket.com/albums/a262/Derek50/Articles/Flattening%20backs%20of%20blades/Bladerestoration4.jpg" border="0" alt="" /> <br /></center>

This worked extremely well. I have successfully flattened several plane and chisel backs. Contrary to what I expected, the blades do not heat up much. In any event, I dunk them frequently in water.

I was able to purchase disks up to 320 grit. The 600 and 1200 I made by gluing wet-and-dry paper on an old sanding disk.

<center> <div><img src="http://i13.photobucket.com/albums/a262/Derek50/Articles/Flattening%20backs%20of%20blades/Bladerestoration3.jpg" border="0" alt="" /> <br /></center>

The leather strop is a piece of chamois leather stretched and contact glued to another sanding disk.

<center> <div><img src="http://i13.photobucket.com/albums/a262/Derek50/Articles/Flattening%20backs%20of%20blades/Bladerestoration2.jpg" border="0" alt="" /> <br /></center>

Here is a result on a blade that was, as I stated earlier, quite pitted.

<center> <div><img src="http://i13.photobucket.com/albums/a262/Derek50/Articles/Flattening%20backs%20of%20blades/Bladerestoration7.jpg" border="0" alt="" /> <br /></center>

And finally the Spier planning a piece of Grey Gum (this has got to be the one of the most difficult woods to plane – unbelievable constant reversing and interlinked grain in a very hard wood).

<center> <div><img src="http://i13.photobucket.com/albums/a262/Derek50/Articles/Flattening%20backs%20of%20blades/Bladerestoration8.jpg" border="0" alt="" /> <br /></center>


2. Building a dovetail chisel


In a recent post Mike on WoodNet showed off his Blue Spruce dovetail chisel. Damn, I want a set!!

<center> <div><img src="http://i13.photobucket.com/albums/a262/Derek50/Articles/chiselscocobolo_lg.jpg" border="0" alt="" /> <br /></center>

Len noted that the side angles were hollow ground. This was one of the features that I found so attractive and had been giving it a little thought as I had been developing a design on rolling my own.

What I have here is the jig I built to hollow grind the sides.

Basically the idea is to use my high speed grinder. This is a 6" machine set up with the Veritas grinder rest and a 60 grit white Norton wheel. While I freehand hollow grind blades, such as those for my Gordon planes, I also have the Veritas blade holder, and I thought that I could press this into service as part of the jig.

I planned to set the side angle at 30 degrees on the practice chisel. To do this I used a Tormek angle setter (no, I do not own the Tormek - just the protractor). It is very useful.

<center> <div><img src="http://i13.photobucket.com/albums/a262/Derek50/Articles/Dovetailchiseljig-settingupgrinder.jpg" border="0" alt="" /> <br /></center>

The jig itself is very simple - just a piece of hardwood into which are set a few rare earth magnets. A section of thin steel acts as a fence for the edge of the blade. It is loose to allow for adjustment, and held firm by the clamp of the Veritas blade holder.

<center> <div><img src="http://i13.photobucket.com/albums/a262/Derek50/Articles/Dovetailchiselgrindingjig-sequence.jpg" border="0" alt="" /> <br /></center>

Note that the jig is inserted upside down here for visibility.

It is used like so ...

<center> <div><img src="http://i13.photobucket.com/albums/a262/Derek50/Articles/Dovetailchiseljig-grinding1-1.jpg" border="0" alt="" /> <br /></center>

Here is a before ..

<center> <div><img src="http://i13.photobucket.com/albums/a262/Derek50/Articles/Dovetailchiseljig-chisel1.jpg" border="0" alt="" /> <br /></center>

.. and after ..

<center> <div><img src="http://i13.photobucket.com/albums/a262/Derek50/Articles/Dovetailchiseljig-chisel2.jpg" border="0" alt="" /> <br /></center>

So the practice chisel seems to work quite well. But I couldn't proceed beyond this point. To my great frustration I only then discovered that the grinder's body projected beyond the 6" wheel and prevented the chisel body being ground in the opposite direction. I shall have to wait until I get a 8" wheel for the machine. So there we wait ..

Regards from Perth

Derek

[JDarvall]

I like that way of flatterning the backs.

But are you shore the result is flat......I know it have to be pretty close...... but whats stopped me from trying similar before, is the spongy velcro that holds the disks on........Does it slightly hill the blade at the corners ?.....uno, just a little daylight at the corners when rulers on .

[DJ’s Timber]

So the practice chisel seems to work quite well. But I couldn't proceed beyond this point. To my great frustration I only then discovered that the grinder's body projected beyond the 6" wheel and prevented the chisel body being ground in the opposite direction. I shall have to wait until I get a 8" wheel for the machine. So there we wait ..


You could unbolt your bench grinder and turn it around, so that it sits on the right of your tool rest. The grinding wheel will be running in the opposite direction but I don't this would be a problem

[derekcohen]

but whats stopped me from trying similar before, is the spongy velcro that holds the disks on........Does it slightly hill the blade at the corners ?..

Hi Jake

Very fair question. In fact, my concern about keeping the blade flat was the reason I avoided using the disk sander before. However, the dial indicator base is very substantial and holding the blade flat is quite easy. I make sure that the bevel area goes on last and comes off first. The scratch pattern tells me that I am getting an even grinding. If you want you can finish off with sandpaper on glass or a waterstone. The disk sander then will just do the donkey work.

Regards from Perth

Derek

[JDarvall]

Hi Derek.

Sounds like nothing to worry about then.

Thanks for sharing the ideas Derek. That magnetic board idea in the jigs looks clever too.

I might pinch that idea, if you don't mind. Can see how it would grip any thin blade easily too....like uno jointer and thickness blades. small blades too no doubt.

Maybe attach a small fence in behind the row of magnets though to keep the blade square....?

My normal jigs require a clamp that extends over both sides of the blade....make its difficult sometimes because the clamp has to be kept thin to stop it running foul of the grinder wheel......but with the magnets, it looks like I won't need support from the underside of the blade, which should give more clearance....and more options. Simplifys things.

Still amazes me how reliable those magnets look (still haven't had any experience with them).... are you shore there isn't a little play ? I mean, does the occation bump shift the blade about on those magnets....cause I can't have that happening in a grind. (if that makes sense)

Goodluck with your chisel.

[derekcohen]

Maybe attach a small fence in behind the row of magnets though to keep the blade square....?

Hi Jake

There is already a fence - that is what the thin steel plate is for. It is just thick enough to support the chisel edge and thin enough to go under the clamp (which has a limitation for thickness).


Still amazes me how reliable those magnets look (still haven't had any experience with them).... are you shore there isn't a little play ? I mean, does the occation bump shift the blade about on those magnets....cause I can't have that happening in a grind. (if that makes sense)

This is the first time I am using them. You can get them in several sizes. I would have prefered larger ones but these were at hand. The chisels I am grinding are narrow. If you are wanting to grind something wider and want the ultimate security, then consider clamps.

Regards from Perth

Derek

[JDarvall]

Hi Jake

There is already a fence - that is what the thin steel plate is for. It is just thick enough to support the chisel edge and thin enough to go under the clamp (which has a limitation for thickness).


Sorry, my mistake. I should have looked closer.

[BobL]

Some good ideas Derek.

I made a slightly hollow ground sided chisel from a 6" triangular file. The sides were hollow ground by accident when I was grinding off the file teeth. Although the sides are not deliberately sharpened I have still sliced my fingers a couple of times with it. The chisel itself is quite hard and takes longer than usual to work up a burr but it stays sharp for a long time so it appears to be good steel.

Cheers
BobL

[woodbe]

Good idea Derek, I have a couple of chisels I might try that back-flattening on...

Are you holding the mag base to the sander by hand or clamping it? I imagine that it could get fairly thrown around the workshop if things went awry. ?

woodbe.

[derekcohen]

Hi Woodbe

The dial gauge base is quite heavy and the magnetic force it exerts is high. Once attached, the blade is not going anywhere. It gives me the control to hold it against the disk manually. Just make sure that you approach the disk as if you were going to set the blade doiwn flat all in one go, but then set the tail end down first and the bevel end last. When you lift it up, remove the bevel end first.

Regards from Perth

Derek

[Bob38S]

Like the idea very much Derek.
Have seen pix of those dial gauges before but not sure what they are usually used for, where to get them and how much.
Thanks for a good idea.
Bob

[woodbe]

You can probably get them at bunnies. Hare and Forbes sell them too.

http://www.hareandforbes.com.au/sample_2/Catalogues/Metalworking/36.html

woodbe.

[Paul Chapman]

Great idea for hollow grinding the bevel edges on chisels, Derek :cool: I think I'll pinch that one - I find the bevel edges on chisels are often unsatisfactory. Thanks for sharing your idea ;)

Cheers

Paul

[W.Lill]

Damn, now I will have to get a disk sander combo :mad:.

Great ideas Derek, and thanks for sharing them

[MajorPanic]

Hey Derek,

I've got a Makita (planer) blade sharpener that is fantastic for flattening the backs of blades. See HERE (http://www.makita.com/assets_product/9820-2/98202_l.jpg)
Because it's a water stone the finish is remarkable without the effort of a stationary stone. The only problem you might (will) encounter is practice. You need a little practice to be able to get an even mirror finish.
Without downward pressure on the blade, it actually aquaplanes and doesn't grind any of the blade. This is very handy when you come to pull the blade off the stone for inspection, just reduce pressure until the blade aquaplanes & then remove as you describe. The original unit comes with a 1000 grit stone & there is an optional 6000 grit stone that is available.

[Clinton1]

And a fine polish it puts on the back of a blade, hey Major?:)

[MajorPanic]

And a fine polish it puts on the back of a blade, hey Major?:)
Well...... it did for yours dinit?? ;) :D

[Groggy]

Hey Derek,

I've got a Makita (planer) blade sharpener that is fantastic for flattening the backs of blades. See HERE (http://www.makita.com/assets_product/9820-2/98202_l.jpg)
Where did you get it? I asked the Makita staff at the WWW show last year and they didn't even know the product existed.

[MajorPanic]

Where did you get it? I asked the Makita staff at the WWW show last year and they didn't even know the product existed.
Groggy,

I wandered down to our local tool supplier 'Trade Tools' (a Queensland company similar to Glenfords) & it was there sitting on the shelf, yelling at me to take it home.......how could I refuse??? :rolleyes: ;) :D :D :D

[Groggy]

Groggy,

I wandered down to our local tool supplier 'Trade Tools' (a Queensland company similar to Glenfords) & it was there sitting on the shelf, yelling at me to take it home.......how could I refuse??? :rolleyes: ;) :D :D :DThese are used almost exclusively by Steve Knight for his lapping processes and he swears by them. So do others I've spoken to who have them. Nice find Major!

[woden]

Derek, I'm just wondering do you use the orbital sander for flattening the backs of blades now or the sandpaper on glass you recently made a thread about. Thing is I've a number of older blades from wooden planes that I could put to use in my Stanley but they're so badly pitted I'd never flatten them just using sandpaper on glass. So I've been thinking of picking up a belt and orbital sander combo.

What sort of quality do you need in one of these machines? I saw in the thread about using the belt section for grinding bevels that your first cheaper version eventually wore out. As I would use it for both bevel grinding and back flattening would I need a good quality one to guarantee durability and to ensure the thing could be used accurately without the flimsiness often associated with cheaper stuff?

[derekcohen]

Woden

If yolu plan to purchase a beltsander combo, then spend a little extra and get one that is cast iron and not pressed steel. You'll thank me later. The pressed steel one's warp with the heat.

Even though I also use a bench grinder, I consider the belt sander to be the superior choice for grinding steel blades.

If you have a plane blade with a pitted back, I would NOT consider grinding this down. Instead I would add a fine backbevel, say 2-3 degrees. That will provide a flat back to the blade.

Regards from Perth

Derek

[woden]

But what if it's a blade for a bevel up plane or even say a chisel that needs an entirely level back without any bevels: is it alright then to grind down through the pits to get a smooth surface?

What are sandpaper costs like for the belt/orbital sander process - is it sore on paper? And is the dial magnet essential for holding the blade to get a level grind? So many questions :rolleyes:

[derekcohen]

But what if it's a blade for a bevel up plane or even say a chisel that needs an entirely level back without any bevels: is it alright then to grind down through the pits to get a smooth surface?

What are sandpaper costs like for the belt/orbital sander process - is it sore on paper? And is the dial magnet essential for holding the blade to get a level grind? So many questions :rolleyes:

Woden

Even a BU plane blade only needs a micro backbevel. As long as this is under 5 degrees for a bed of 12 degrees (since there needs to be about 7 degrees clearance), then you will be fine. Grinding down the entire blade back is a LOT of work, and unnecessary.

You can grind down a chisel back. You cannot use a backbevel on a chisel.

Belts for beltsanders vary in quality and longevity. Some used for honing (not grinding) edges have lasted 2 years. Some used for grinding metal, used heavily, last 2 hours. It depends on the use and quality.

Regards from Perth

Derek

[woden]

Thanks for getting back to me, Derek. If you use a back bevel on a bevel up plane does it not undermine one of the planes strengths: the blade being supported by the bed to very near the tip? Surely, with a back bevel the section of the blade near the tip won’t be supported by the bedding!?

Is at least 7 degrees of clearance needed on every type of plane blade?
<O:p</O:p
Which in your experience is fastest at removing steel when sharpening – the belt sander technique or using a high speed grinder (or low speed if that’s faster as some argue)?

Sorry about all the questions but I still know very little at this stage. :-

[derekcohen]

If blades are thick enough (1/8"), then a backbevel will not affect stiffness or bedding issues.

The fastest way of grinding a lot of metal is the one that runs the coolest. This is a belt sander - a long and wide and coarse belt discipates heat best.

Regards fro Perth

Derek

[woden]

Must check the thickness of the blade in my Record 073. I've been trying to flatten the back of it and a back bevel would really speed things up - would near an 1/8 be thick enough to avoid stiffness problems. I know, I know, how long's a piece of string but I do think it's close to an 1/8th.

Well if the belt sander is faster than the grinder as well as avoiding the overheating problems and allowing you to flatten blade backs it sounds like the business then. A combo would seem to be superior in just about every way to a grinder. Do you know if a lot of people are switching to the sander since you did your threads on its uses for grinding?

If your clearance angle is less than 7 degrees but still greater than say 0 what affect will it have on the plane? You see I ground the bevel on my 078 plane to 41 degrees giving a clearance of only 4 degrees. The plane is quite hard to push and I'm wondering if the lack of clearance is the culprit; I can't compare it to any previous use with greater clearance as I've only ever used the plane since re-grinding the blade.