Help sizing wooden rounds and hollows

[Hornbeam]

I have a job which has some fluting so decided to buy a matching pair of wooden rounds/hollows.
They are the same maker and both are stamped as no16.. Bothe blades are 1 1/4 inch wide which corresponds to a No 16
I expected the sole profiles to be an exact fit, however the round is significantly tighter radius than the hollow.
Is this normal?
If not I could adjust one to fit the other but how do I determine which is a true 16 curvatur
Thanks in advance
Ian

 

[Droogs]

Looks like you have a pair but not a matched pair. They were normally made at the same time by the same man and matched perfectly before being sold. At some point yours have come together (been put together by someone who never used them). Seems a dealer has had size 16 in each from the same manufacturer and just stuck them together.

It is worth noting that each manufacturer had their own sizing system, even if they used the same numbering system. so no 16 would match any other generally. The only time they would is when first made and if kept together. Very much the same as in the size of sweep in carving gouges from different companies.

At least you will be able to get the results to match a lot easier than if the mismatch was the other way round, just a couple of extra strokes at more acute angles

 

[Argus]

Is it possible that your pair, if not an exact marriage from manufacture, were altered during a previous ownership?

I did hear of carvers altering H&R plane profiles for a particular purpose, typically in roughing out linen-fold blanks where they may have desired an elliptical profile over a circle for the curvature. Personally, I have used a so-called 'pattern-makers' plane in conjunction with a couple of (unaltered!) H&Rs for this purpose.

In general, though not exclusively so, the curve of a particular size in a H&R pair are considered a 60 degree segment of a circle. You may consider offering up a radius gauge of the correct size or constructing a rigid profile in, say, plastic based on the correct radius to see which is not quite the right before making any alterations.

P.S. - Always check the sole of the plane; if the blade is presented at a skew (which some are) it's curve won't be circular.

.

 

[Hornbeam]

At least you will be able to get the results to match a lot easier than if the mismatch was the other way round, just a couple of extra strokes at more acute angles
[/QUOTE]
I dont see how you can change the angle as the sole profile must follow the frofile you are cutting in the piece being profiled

 

[Hornbeam]

n general, though not exclusively so, the curve of a particular size in a H&R pair are considered a 60 degree segment of a circle. You may consider offering up a radius gauge of the correct size or constructing a rigid profile in, say, plastic based on the correct radius to see which is not quite the right before making any alterations.

That is exactly what I think is the best way forward. Understand that there is some variation between makers. between different planes when new and the effects of general wear and tear. I think that a no16 hollow /round should be 1 1/4 inches cutter with and have a radius of 1 1/4 inches (6 X cutter width equals a hexagon within the circle of 1 1/4 inch rad)
Ian

 

[Argus]

These things came in sets and half-sets originally, with the numbers usually rising in 16ths (No: 6 = 3/8", No10 = 5/8" etc.) until about the 1 inch mark where it went to 1/8th graduations....... different makers had different ways of doing it ..... I don't think that they got much bigger than 1 1/4 or 1 3/8 inch.

I guess that you are down to a bit of experimentation if you feel that they are not right. But in reality, unless they are miles out of sync the eye is very forgiving of small errors.

But to see for sure, cut a series of radii and see which fits best. Work on one plane at a time..... Personally, I'd start with the hollow...... get that right then see if the round needs any work.

The obvious way to make any alterations, if you feel that you have to, would be to 'mother' the hollow profile from the round by using it to plane the hollow's sole. I would NOT do this - it will result in a sole out of true.

If you need to make any adjustments, and once you have an idea of the radius, get some abrasive and glue it to a straight piece of round dowel so that the resultant overall curve is exactly the radius that you need. Work slowly, a stroke at a time testing for straightness. When the hollow bed is right work on the round's bed in the same way. Make an abrasive former that is the exact size, working one stroke at a time until you have a fine fit between the two. from this you can slowly work on the profiles of the blades so that they echo the shapes of their respective beds, tapering away at the corners.....
Good luck!

 

[Hornbeam]

My feelings based on measurements and condition is that the hollow is the correct dimensions. i have sharpened this and it is now producing a very nice finish and profile.
I will sharpen the round and and see what it produces and then adjust if required

 

[Nigel Burden]

I bought a job lot off ebay a couple of years ago, and in it were four hollows and rounds. Two were No 6s but they were both hollows ie. convex. I planed and squared the sole on one of them and then clamped a piece of board in the vice to act as a fence and used the other plane as a mother checking for flatness. Then I reshaped the iron by bluing it with permanent marker and scribing the profile, then formed the bevel finally polishing out the bevel with different grades of wet and dry wrapped over a dowel. The result seem satisfactory.

Nigel,