Handplane sole flatness

Re: Handplane sole flatness

Derek Cohen (in Perth, Australia)

>Oh Boy, this topic has the emotion to start a heated exchange! So many opinions...

As always, try before you do any work. It may just perform well (enough).

Also, we are really only talking about smoothers and jointers - less precise planes, such as jacks, do not warrant the extra work.

My take is that flattening a sole improves performance. Now read that again - I did not say that it was the flat sole that improved performance, but the process of flattening the sole. What happens is that you get the area in front of the mouth flat, and then this area is co-planar with the toe and the heel of the plane. Now you're in business! The clean edges at the front of the mouth also guarrentee that this area provides maximum support to a closed down mouth of a smoother.

Regards from Perth

Derek

Re: Handplane sole flatness

Joe Rogers, Northern Virginia

>Whoa Stuart...this is a question that has many answers. Some people think that the only good plane is perfectly flat. The other camp will try out a plane to see if it works before they spend any time flattening the sole. I would check any planes you have by using a straight edge before I devoted any effort to a badly out of true plane.

If you decide to true a plane the methods can include loose abrasive on plate glass, abrasive paper or sanding belt on plate glass or an other true surface. Like a surface plate for instance. They can be scraped to true, or even machined to specs. A very controversial thread begun by Forrest Addy even advocated a convex plane sole.

Different strokes for different folks. Other Islanders will probably chime in with some thoughts and if you do a search in the archives you will have hours of reading ahead.JR

It is not easy

bill tindal, E.TN

>I can't offer any quantitative advice on how flat it must be, but if you want it flat take it to a machine shop and get it surface ground. It is very unlikely most people will be successful flattening a sole unless they have experience in doing this sort of thing. I can say for a fact that various people in the club have tried it and wound up at a machine shop. No doubt someone will provide an exception to this rule, and you may be one yourself. Personally, for this reason I don't buy a plane unless I can measure its flatness before hand.

Re: My limited experience

Glenn Madsen near San Francisco

>with old planes has indicated that, as flat as I can get it with wet/dry sandpaper glued to MDF does everything that _I_ need it to do.

Are there folks who can get it flatter? Certainly. Do I really care? Not so much so. There is only so far that _my_ work needs to go towards perfection, and I'm not nearly as AR as some of my buddies in the woodworking club, although I am somewhat fussy.

Old planes are just that. My uncles did some pretty nice work with the old stuff in their tool totes. I was embarrassed to talk tools with my uncle before he passed away last year. I probably had four times the number and types he had, just no where near the experience he did. He did very nice work.

Stuart.......

Todd O. Cronkhite Maine Native, Presently Away

>I'm curious as to why you feel the soles need to be flattened in the first place.

As has been stated this is a topic that will cause much heated discussion at best, and has been discussed time and time again already. Again, as has been suggested,do some archive searching and you'll find more than you want to know on the subject of sole flattening.

We had one fellow who diligently flattened soles thinking that he was doing good, than discovered that instead of making his planes better he had actually made them much worse.

I have bought many a plane from the flea markets and have never once found one that needed the sole flattened. Once de-rusted, blades sharpened they performed flawlessly, so I say flattening a sole is pretty much a foolish folly.

So,again, what makes you think they need flattening in the first place?

Todd O.

Re: Handplane sole flatness

Stuart Hough

>Thanks for the advice of checking the archive. I'm sure I'll spend many an hour there, as I'm sure there are as many opinions/ideas as there are woodworkers. I'm still fairly new at this stuff, that's why I asked for the info. As far as I can see, I don't have any really out-of-whack planes, but am interested in making them as good as I can so I can do quality work. So far I have used the sandpaper-on-glass method on one of my block planes, just to see how much work it would take, and I now have it so that the area in front of the mouth is completely shiny, as is the back 2/3 of the plane. I seem to have a slightly dished area (about a cat's hair deep) from 3/4" behind the mouth to about 1-1/4" from the heel. I'm guessing that's as for as I need to go. Thanks again for all of the responses!

Good clean fun

Jim in Burlington On

>My tools for flattening. I large 1/2" thick used glass coffee table picked it up at the reuse center for a couple bucks. 90 grit lapping powder. A little 3 in one oil and a scraper. If you have a really nasty high spot get a single cut file. Start with the cheap small planes. Finish it off with sandpaper glued to the other side of the glass. Usually takes between 2 hours but a big plane like a 608 took me along time spread out over several days.

My First Plane....

Warren in Lancaster, PA

>I bought my first plane about 35 years ago. It was an iron plane and I did not know to check the sole. After about a year I made a wooden plane and took a lot of care to plane a flat sole on it. When I tried the wooden plane I was very surprised how much better it worked. Then I checked the iron plane and found I could see 1/16 inch of daylight under the straightedge. I was actually able to compensate for the sole and plane a surface very much flatter than the plane had. Of course it worked better after I did some flattening.

I would recommend checking the sole with straightedge and filing the information in your head until after you have learned to use the plane. If you notice the behavior of the plane fits with oddities in the sole you can then worry about flattening. If you flatten before getting used to the plane, you rob yourself of the chance to get a feel for how flatness actually affects the behavior of the plane.

Put your energy into sharpening...

John in New Mexico

>The cutting edge matters a lot more than sole flattness IMHO. I could see a drastically concave sole like Warren described causing problems, but other than that it doesn't matter a whole lot if your ultimate goal is to make furniture and such. If the ultimate goal is to make the perfect plane, then it may matter, I wouldn't know.

John

Bench test and the geometry of flattness--long

Jim Reed @ tallahassee

>The first thing I do is give the plane a bench test. Protocol is as follows: 1) Sweep bench area clean with horsehair brush 2) Put plane on bench and try to rock it 3) Look for air in the gap 4) If problems are noted, follow up with surface plate test. If five minutes of sandpaper does not fix the problem, I reject the plane and sell the parts that are usable. It helps if you start with a good plane in good condition.

This is all simple geometry--flatness is where the points exist in the exact same plane. Now do the math on flatness--first you have to determine your resolution, then you measure the points and calculate the difference. Using just pinhead resolution gives you thousands of points to measure. This mental geometric exercise demonstrates that true flatness is impossible except at very low resolution. Some lack of flatness is of no consequence--just look at corrugated planes. By definition, they should be twice as flat because there are 1/2 fewer data observations. The quest for an absolutely flat sole is a fool's errand. Other factors affect performance, not just flatness of sole and too much attention to flatness can be a waste of valuable shop time.

Japanese planes are not flat, and they work

wilbur

>Just to echo Derek's point: Japanese planes are deliberately designed to not have a flat sole. What they do have is that the edge near the front of the plane and the area immediately in front of the throat (and sometimes the edge at the back of the plane) are coplanar. The majority of the sole of the plane, between the front edge and the area immediately in front of the throat, is relieved, so that there is a very slight concavity in this area. With a well tuned Japanese plane, if you took it to a reference flat surface, sprinkled graphite on the surface, and rubbed the sole of the plane on that surface, you would only see graphite marks on the front edge and a thin strip in front of the throat.

And, yes, they can plane a very flat smooth surface even though their soles are not flat al the way across.

Re: Japanese planes are not flat, and they work

Pam Niedermayer - Austin, TX

>Yes, you're absolutely correct, Wilbur; but I want to add that convex soles don't work at all, except for those intentionally convex planes like compasses and spoons. I know you know this, but maybe Stuart doesn't.

Pam

... in the eyes of the beholder

woodburnbob

>I congratulate your heroism, Stuart, in asking the question. As you peruse the archive, you're sure to conclude that complete lack of consensus reigns. It's as if half the country were Republicans and the other half Democrats. Or, pick any of a number of religious analogies. But do at some point ask yourself what this degree of contradiction actually means. This really is a sort of philosophical right of passage issue for plane guys and I think pretty much separates the shallow from the deep.

In your mental journey be sure to think about the intricacies and limits of a plane such as the Stanley #20. Here you can set the plane sole to be flat, concave or convex at will. Imagine, if you will, the outcome of using such a plane as the #20 on a flat board successively under each of those three configurations.

Many old planes, metal and wood, have a dished out funnel-shapped trough in the toe that ends at the mouth. It testifies to the insidious abrasive powder of wood and is pretty dramatic evidence of accumulated erosion over decades of use. Given one of those planes in its "wild", as-received condition, can you speculate on the nature of the shavings that will come out of that plane, assuming a straight cutter edge? Many guys might say such a plane works great; one can immediately understand their characterization of greatness.

At some point in your use of planes, you are going to notice one that stalls and chatters, skids and chokes. If there is nothing else you can do to fix it, I'd bet the sole's concave in the long axis. It will skid and touch no wood until you project the cutter edge far enough to catch a sliver of wood. The cutter will then dive, the sole flexes, the cutter dives further, movement stops, and there's now a big wow and tearout to mark the spot. You utter a curse. If you remove the concavity, things will be better.

Similarly, if your jointer has a convex sole, by necessity you will in time produce a concave edge of the same radius. Explain how it could do anything else.

Back to your original question: I think a practical answer is that you flatten the sole of a bench plane when you have a problem with performance that you think ought to be corrected by doing it, given the data you gather from inspecting and using the plane. For planes like Bailey #3, #4, #5 I'd say a rule of thumb might be absence of a concave sole by the 3 paper test. Cut 3 strips of paper 1" wide. Put one under the toe, mouth and heel while the plane sits on the flattest surface you trust. Paper thickness is in the 0.001" to 0.003" range. If you can pull out the slip under the mouth, your sole is concave enough to give you chatter, flexing, tearout and headaches. I've read guys who say they can dynamically flex the sole while in use by variably flexing their wrists while gripping the knob and handle. I don't take androgenic steroids, so there's no point in my trying that.

Re: Handplane sole flatness

paul womack

>How close to perfectly flat must a plane sole be?

I think (as a starting point) toe, mouth and heel should be co-planar to around the tolerance of the finest shaving you're planning to take.

BugBear

Re: flattening

paul womack

>The nest, most obvious question would be, what is the best/easiest way to get to flat?

I (and a number of metalworkers) do not consider rubbing on an back abrasive (what woodworkers call lapping) accurate or efficient.

Here's my evolved approach.

flattening using a reference

BugBear