Lapping a Plane Sole Flat, Advise Wanted

[Stew Denton]

Hi All, I am wanting to flatten the soles on a couple of my larger planes. I have a large granite stone, specifically made with an ultra flat surface I can use for my smaller planes, but it is too small for my bigger planes.

What is a good set up to do this with? I know David mentioned in another post that it is not difficult if you have the right set up.

Do you use special metal cutting sandpaper, etc., and if so what brand, product number, grit size, etc., do you use? What do you use to glue the stuff down, etc.

Also, it seems like a read a while back, while just a reader of the site, that one of they guys here is a machinist that will mill the sides and bottom flat, am I correct in this?

Any help will be appreciated.

Thanks and regards,

Stew

[David Weaver]

If you have a power tool surface that's absolutely flat in some dimension, that's good to use. If you have a bench that's very flat, then finding something supplemental to use on it is a good idea.

I have always used an 8x42x1/2 inch piece of glass on a flat bench surface. I use Mirka gold (doesn't matter the brand) aluminum oxide PSA stick down paper. PSA is important, as any paper that is not stuck down will dub the toe and tail of the plane in question. It won't render it unusable, but there's no reason for such ugliness, and the PSA paper can be used in push and pull directions.

That's pretty much it. Use the plane with the blade retracted and push the plane with the handles or with a hand between the handle and frog, as if you were using it. No wailing around is needed. If we are talking about a long jointer, sometimes it's easier to take a small block, say 2x3 and use 60 grit paper to do bulk removal of metal before final lapping, but I have also lapped #7s in a half hour or so on good fresh 80 grit al-ox paper/rolls.

Less is more lapping planes - get things as flat as they need to be and then stop.

[Derek Cohen]

I have a one metre length of granite (cheap offcut) to which I glue sandpaper ...



Edit to add:

1. Care must be taken to keep the sole of the plane very, very flat to the surface of the sandpaper. There is the constant danger that the plane will rock, and then this will round the sole, either/both along the length and width. Next push the plane forwards only; push forwards and down.

2. Sandpaper should be seen as a way of finishing - not starting - the lapping process. It can aid in finding high spots on the sole. These are - ideally - scraped away first. By the time one gets to sandpaper, the sole should be fairly flat.

Regards from Perth

Derek

[Jim Koepke]

Are you sure the sole of your planes needs lapping?

Is it end to end, side to side or a bit of both?

I use a hunk of granite that came from a monument maker for $25. It is as flat as can be checked with my straight edge.

Granite on Horse.jpg

One thing is to be careful and constantly check what you are doing. The filings can collect and make your efforts go to making the sole worse. Especially be careful about not rounding the sole side to side.

jtk

[Tom Bussey]

I grind them.
DSC01547.jpg DSC01548.jpg DSC01549.jpg I grind them.

[Dave Parkis]

Tom Bussey from the post above is known as Tableasaw Tom and he will grind the sole flat and the sides perpendicular to the sole. His prices are reasonable and his work is excellent. I'm sure others will also recommend Tom.

[Mike Holbrook]

If you decide to do it yourself Highland Woodworking sells roles of 3M Stikit, PSA sandpaper in a couple different widths and a selection of grits. It holds reliably and it comes up off a metal or stone surface relatively easily too. You may be able to see a piece in the pictures I posted on my refurbishing planes thread in this forum. In my pictures the Stikit is stuck to my tablesaw table.

[Stew Denton]

Tom, I tried a couple of times to send you a private message, but obviously don't know what I am doing yet. I will try again tomorrow.

Also, thanks to all for the advise on this topic so far. Jim, you are right, I have not checked the planes I have, so need to check them for flatness and squareness. I just assumed that they were neither flat nor square.

Thanks and regards,

Stew

[Bob Jones]

Coarse sandpaper (initially), a good straightedge, a lot of patience, know where to apply pressure to selective remove high spots, know when to stop. Go from 80 grit to 600 grit. Alternative - Ignore all of this and ship them to Tom for grinding. Up to you.

[Steve Friedman]

Tom Bussey from the post above is known as Tableasaw Tom and he will grind the sole flat and the sides perpendicular to the sole. His prices are reasonable and his work is excellent. I'm sure others will also recommend Tom.

Absolutely. Unless you are bored and have nothing else to do, Tom's work is impeccable. I doubt that level of precision can be replicated by hand and his prices are extremely reasonable. He'll also do the sides if you plan to use it for shooting. He'll also do the frog.

As an added benefit, when you go to sell the plane, it will get a premium for having been in Tom's able hands.

Steve

[Mike Holbrook]

Flat or shinny?

So I decided to check out my Stanley 6C's bottom and sides for square/flatness. Using my engineers square the bottom was not showing any issues that my naked eye saw significant light through/under/around. I keep a piece of 3M Stickit on my tablesaw table (it's main use now). I ran the plane bottoms and sides over it a few times. I could see a few gradual, small high spots and so I spent a little while lapping, particularly the bottom. I have a LV BU Jack & Smoother if I want to shoot something. Checking the 6C's bottom now I am having a very hard time seeing anything significantly out of square. The bottom is not shinny all over like it would be if I worked down to a low grit making sure the whole bottom was dead flat. I think for my purposes I will not see any difference in workpieces if I go further with flattening the bottom.

My question is whether or not I now have, for practical purposes, a flat bottom? It seems to me that further work would fall into the realm of beauty treatment rather than practical improvement of the functional ability of the tool to do the work. Is there any reason to proceed further with the flattening process that I may not be aware of?

[David Weaver]

I'd stop where you are now and use the plane. If you don't notice any issues while using it, then there are none.

[Jim Matthews]

I use a hunk of granite that came from a monument maker for $25. It is as flat as can be checked with my straight edge.

Granite on Horse.jpg


jtk

Ahh - the infamous photo that started it all...

My wife called this Arnold Schwarzenegger's sawhorse, because only weightlifters could move it.

[Jim Matthews]

If you don't notice any issues while using it, then there are none.

If Star Wars had been a Home Repair show, Yoda would have said this.

[Curt Putnam]

If the plane takes shavings that you want, it ain't broke and don't fix it.
If it is broke (not flat - not square - does not take good shavings) send it to Tablesaw Tom (Bussey). Unless you have a lot of skill and experience, lapping a big plane should be left to the pro. I have several planes that he has ground and they are superb.