granite vs. float glass?

[Dave Lewis]

I have several older (not antique) planes that I should flatten the bottom (soles?).

How do 1.5"-2" thick granite cut-offs compared to float glass for this purpose?

[Vincent Tai]

depends on how flat the granite is. If it's flat and nice and long then go with it. Float glass can be shimmed a little. Float glass on top of a granite cut off with some sheets of paper under to shim things to flat makes for a nice cheap and useful flattening substrate. For smaller planes, blades etc, (anything that finger pressure can easily lap a bow, convexity into you can shim the glass so it is convex just a touch. Helps with those small items.

[Jim Koepke]

I have several older (not antique) planes that I should flatten the bottom (soles?).

How do 1.5"-2" thick granite cut-offs compared to float glass for this purpose?

Do you have some way of determining how out of flat the bottoms of your planes may be?

If a plane isn't displaying a problem associated with the sole being out of flat, it is likely not in need of a sole flattening.

jtk

[Rob Luter]

Float glass can flex if it's used on a surface that's not flat. I use the top of my table saw and sandpaper for this purpose.

[ken hatch]

Do you have some way of determining how out of flat the bottoms of your planes may be?

If a plane isn't displaying a problem associated with the sole being out of flat, it is likely not in need of a sole flattening.

jtk

As we would say back when the world was mostly sane or at least I was young: Right on brother.

ken

[Ralph Boumenot]

I use a 36" threshold from Home Depot for my planes. I don't use it to flatten them but to sand and shine them up

[ken hatch]

I use a 36" threshold from Home Depot for my planes. I don't use it to flatten them but to sand and shine them up

As sure as the Sun rises in the East Ralph's planes are shiney. He knows of what he speaks:). BTW, if you would like to see some great plane restorations check out Ralph's blog https://accidentalwoodworker.blogspot.com

ken

[Frederick Skelly]

As sure as the Sun rises in the East Ralph's planes are shiney. He knows of what he speaks:). BTW, if you would like to see some great plane restorations check out Ralph's blog https://accidentalwoodworker.blogspot.com

ken

Man, they sure ARE! Nice work Ralph! (Hope your cold improves.)

[Allen Read]

Both granite and float glass can bend a little. The thicker either is, the less that it bends.

With granite, be sure that the back is as flat as the face. If it's not flat you can use thinset or leveling compound to support it from bending or better, move on to another piece. In years past, granite was cut with wire saws and the thickness was very inconsistent. In the last few decades, they have moved on to diamond gang saws that produce a much more consistent thickness. It's not perfect, but, it's much better.

Your 1 1/2" thick pieces should be great for flattening your planes. I use a 12" x 24" x 3 cm piece of granite for flattening. I'm in the business, so I was able to select a piece that's consistently flat on both faces. Fortunately this was easy.

Be sure to fully support your granite. While it seems stable as a rock (sorry for the pun), it can flex a little if not fully supported.

Allen

[Bob Leistner]

I'd be willing to bet more people knock their planes out of flat than ever make them better. It is too easy to be inaccurate. Leave them be unless you're 100% sure that they can not work as is.

[bridger berdel]

Float glass can flex if it's used on a surface that's not flat. I use the top of my table saw and sandpaper for this purpose.

Glass can flex quite a bit even if it's sitting on a flat surface. Surface plates are thick for a reason- to overcome flex

[Rob Luter]

Glass can flex quite a bit even if it's sitting on a flat surface. Surface plates are thick for a reason- to overcome flex

I guess I'm not seeing how this can happen, unless the flat surface it's sitting on is also flexible.

[ken hatch]

I'd be willing to bet more people knock their planes out of flat than ever make them better. It is too easy to be inaccurate. Leave them be unless you're 100% sure that they can not work as is.

Bob,

I couldn't agree more. If you are sure the sole needs work your best bet is one of two things: Sell the plane to someone (not a friend :D), or send it to a machine shop. Another option is to turn it into a roughing plane, scrub or jack. BTW, you should see the sole of my 30 year old wood stock scrub plane, ain't no way no how a metal plane sole could be a bad and it still works a treat.

ken

[Brian Holcombe]

A milling machine and fly cutter :D

check to see if they’re flat before you work on them. How far out and where they are out matters. A touch up at the ends isn’t noticeable and I could live with the center slightly up on a long plane.