Spokeshave Challenge

[RobinW]

I have never mastered the spokeshave, and as I am currently making a child's rocking chair with various curved lines, I am now determined to get on top of this tool.

Staying with one model in particular, a Stanley No63 (of many years vintage) which has a curved base. I could not get it to give a decent cut on any hardwood. So to get up the learning curve, I picked a nice piece of mahogany, 22mm, wide as the grain is very uniform.

I thought the mouth too wide which was causing a lot of chatter and rough cutting. So I put a plastic shim behind the blade and this helped a lot. However the cuts were not uniform across the wood, and this was due to the blade not being parallel to the top of the mouth.  I realised that although the top and bottom edges of the mouth appeared parallel, the face on which the blade fits (like the frog in a plane) is not parallel to the top of the mouth, causing the blade to sit squint to the top of the mouth. This is an original casting issue.

I then used a piece of thick paper behind one side of the shim and this made the blade sit parallel to the top of the mouth, and I was then getting some nice full width shavings from the mahogany.

So I am now left with how to sharpen the blade. I have previously done it on Japanese wet stones but this is a pain due to the small side of the blade, and so I am looking for advice on how to sharpen the blade on my Tormek.

The blade is 1³/₄" (45mm) wide 1³/₈" (35mm) from to back, and ¹/₁₆" (~2mm) thick, so the SE76 won't look at it.

I haven't tried it yet, but I doubt the SVD 110 is the answer as the small blade means it would be finger pressure down on to the SVD110 as the only means of holding the blade, and I doubt if this would give accuracy across the blade.

Also what angle to grind? At the moment it is 25 degrees, but if I increase this to 30 degrees this may also reduce the chatter.

So suggestions welcome.

[Herman Trivilino]

I'm sure you know this, but the direction in which you run the tool may make a big difference.  You'll get more chatter in one direction because you are splitting the fibers, whereas in the other direction you are slicing them.

[RobinW]

I only used it with the grain. If I made an error and went against the grain there was (as expected) big tear out just like a plane would do.

Even going with the grain there was a lot of chatter and ridges across the direction of the cutting path. Angling the tool against the direction of cut, so the effective cutting angle changes, improved things a little, but too erratic to give a proper solution. When it did go well I could get a good surface finish.

[Mike Fairleigh]

I'm not a shave expert at all, but I would think using a curved-sole shave on flat wood would be very difficult to avoid chatter.  Does a curved-sole shave assume that you've already formed the rough curve?

[RobinW]

The curve has already been made on the bandsaw. The convex part I smoothed using a No 3 plane, but the concave part is too tight a radius for a normal plane and I don't have a compass plane.

I also got chatter on a straight piece of wood. Closing the blade to the top of the mouth improved matters a lot, but not perfect.

My main issue at the moment though is how to get this small blade sharpened. If I can somehow get this held on the Tormek and really sharp, then I can come back to the chatter. The blade has been pretty sharp as done by hand, so I'm just hoping that if I can get it sharper whether this shows an noticeable improvement.

[Mike Fairleigh]

Any chance the small knife jig would work?  What angle is the blade sharpened to?

If you're getting it truly sharp on water stones, I have a feeling it isn't going to get better on the Tormek but I could certainly be wrong.

[RobinW]

The blade is currently 25 degrees. However trying to hold a small blade like this and use waterstones is tricky and my finger joints let me know it! I did flatten the back, and that was a real pain to get done.

[RobinW]

I've just had a look at the SVM00 and SVM45. The SVM00 had a piece covering the end and is shaped for handles, so that wouldn't work.
I thought the SVM45 was for curved blades, but it should do a straight edge if careful. (I don't have one so need to investigate) It has the right sort of clamping which would hold the spokes have blade. Need to look further.

Thanks for the clue.

[nobby1967]

Are you pushing or pulling spokeshave. try using like a draw knife.

[RobinW]

My SVM45 has arrived and I have now sharpened three different spokeshave blades (two of which are slightly bigger than the sizes quoted above), all at 25⁰, no micro-bevel. This was another learning curve, and nearly collected a Tormek tattoo on the way!

I previously had great difficulty holding these small blades when trying to sharpen them on Japanese waterstones, and there was no way I could hold them when to use the SVD110 and they are too short for the SE76.

The SVM45 now gives me good holding jig, so I flattened the backs initially on the side of the wheel then finished off using waterstones.

I also honed up the bases of all three spokeshave bodies.

I started with grinding towards the edge of the blade, and this led to a couple of 'moments'! The tool caught and jumped a bit, but I managed to avaoid any problem. A couple of minutes later it caught again, spun the blade end of the SVM45 under the universal bar, hit me in the chest, fell to the concrete floor and took a bit bit out the blade!

So I rearranged to grind away from the edge. It is not easy to stop the tool angling sideways (as you would like it to do when following the curve of a knife) and trying to maintain a straight cut. However I got there. I did find that I appeared to get a better edge if I removed the wire on the edge using the waterstone. Using the leather honing wheel I must be rounding it off and loosing sharpness. Also I did not hone the bevel side, I just 'polished' this up with the wheel fine graded and light touches.

To the No 63 and another curved spokeshave I used shims to close the gap, and just tweaking the blade positions, I managed to get these two curved spokeshaves working pretty well in concave cut mahogany. The grain is changing from almost end grain at the top of the curve to fully with the grain at the bottom, and I have made some very smooth sweeping curves.

The flat bottomed spokeshave, didn't need any shims, and went well along the grain. Overall a big improvement.

I think I know why the blade caught. It is 45mm wide, and I probably went too far over the edge of the wheel, and as the SVM45 can rotate (unlike the SE76) the blade went over, caught the corner of the wheel, and decided it would like to take up gymnastics! Bit of scary. This is less likely to happen with a knife as the blade is probably longer and you have its handle to control any angular moment. So a word of caution to others when using spokeshave sized blades - grind away from the edge.

[Mike Fairleigh]

That's a good point about traveling beyond the edge of the wheel.  I've learned that one of the subtle necessities with the Tormek is to keep the pressure over the wheel.  In other words, it's OK if the blade goes off the edge of the wheel (even when grinding into the edge), but your fingers must stay over the wheel at all times.

[RobinW]

I have made a mock up of a new jig which I believe will solve the problem of sharpening small blades like those in spokeshaves, and the problems I experienced as posted previously. Herman's HK50 is fine for items which you can get a good hold of and keep stable as you grind, but I have great difficulty holding small blades.

The SE76 is not designed for blades which cannot extend say 50mm from the jig. The SVM45 knife jig can handle small blades but is susceptible to snatching if the blade is not very wide and the operator goes too far over the stone edge (as I demonstrated!) and can introduce angular issues in grinding as it does not have anything to prevent any shaft rotation.

I do not have a milling machine so have not made a working metal unit. I have made a wooden mock up to demonstrate the principle and show that the dimensions are suitable for use.

Copying the clamping arrangement as used on the front end of the SVM45 and making a mock up as shown in the following photos, you can have a tool which clamps a small blade as shown in Pic 1 and Pic 2. Width of mock up 45mm. Thickness of baseplate 9mm. Thickness of clamping plate 6mm. Outside shaping and recess for the blade the same as the SVM45. Overall length of mock up 110mm.

The spokeshave blade in the pictures is 35mm front to back.

Pic 1


Pic 2


The marker pen sketches illustrate the same type of screw fixings as used on the SVM45.

Pic 3 shows the jig mounted in the SE76. The base plate of the jig is butted up against the right hand side of the SE76 just like a plane blade, so registers the same.



Pics 4 and 5  show the whole assembly mounted on the T7 with a bevel angle set at 30 degrees.





Caution - This wooden mock up is to demonstrate the principle, and should not be used to sharpen any blades. A properly machined metal version only should be used.

I am happy to share this with contributors and Tormek alike for no cost. If Tormek make and market one, a free sample wouldn't go amiss. All Tormek have to do is replace the round shaft on rear end of the SVM45 and extend the existing bottom plate. They have all the dimensions and tooling in place for the rest. (Tormek should be quick off the mark as no doubt their competitors will check through this forum and monitor the problems, solutions and ideas raised by contributors.)

[RobinW]

Apologies to anyone I may have confused. In my post above I should have used SVM45 not SV00 ( getting the jigs confused after the other posts about holding small knives.)

**I have now been back into the previous post and changed SV00 to SVM45**

[Herman Trivilino]

Nice work, Robin.  Have you used the SVM-00?

By the way, you can go back and edit that post, fixing the typo you made with jig names.  You make references to both the SVM-45 and the SVM-00, so it would help me understand which one you were talking about.

[Rob]

to edit a post look for the modify buton in the top right corner of the post