thinning back plate

[peter havriluk]

I have three backs to thin. Already joined with backstrips. I'd like to get from .125" to .100". Don't have access to a thickness sander. I do have a RO sander, jack plane, block planes. And a flat place to work (granite surface plate). And I made a thickness gauge at Ken's suggestion, so I can measure thickness anywhere on the plates.

Suggestions at to how to do this with the tools at hand? Warnings? (I already have encountered runout, so I know to plane in a direction that won't dig into the surface).

Thanks, folks.

[John Parchem]

I would have waited to put the back strips on. To keep the best book match. once I have the outside of my plates sanded flat I remove wood from only the inside. The more you take off of the matched side the worse the book match gets. Even If I was thinning from the outside the back strip keeps the plate from laying flat.

I would use the jack plane going diagonal to the grain.

[peter havriluk]

John, I considered sanding the plates independently and then joining, and I decided that I didn't want to deal with the plates' being thinned too much at the backstrip join, being at the edges at the time of planning. I knew that one pass too many with a plane would be an unhappy event, and I wanted to avoid that. Now, at least, any excess thinning will be in the areas that will be cut off at the perimeter, not the middle. Or so I 'reasoned'. I did use a cabinet scraper to level the backstrip to the plates, and I'm pleased how that turned out, no bulges that I can see. And no hollows.

But I'm embarking on a course of learning to use the jack plane. As long as I keep the shavings as thin as I can, I think I might avoid trashing a back. I hope.

Thanks for the advice,

[John Parchem]

I am sorry I misunderstood! I was thinking about the cross grain reinforcing back strip. Not the decorative strip. Whoops. Of course you should have joined the plates first. The rest of my answer is still good.

[peter havriluk]

John, I sometimes cloud a topic as I try to explain it...did it again, I think. Good thing I never tried to earn a living doing technical writing. I can see how I alarmed you if the reinforcement strip was making a big lump out of itself.

And now that you've rung the bell about the crossgrain reinforcement, I'm open to suggestion as to when I install it. Easier to do it all at once before the braces are installed, but then it needs to be carved away where the braces traverse. But installing it in pieces seems like that would be a recipe for unevenness of the back. Binary choice here, before or after braces? I think I'd like the reinforcement to be the first thing installed on the back, braces to follow, but this is my first solo trip on this task.

Thanks again.

[John Parchem]

John, I sometimes cloud a topic as I try to explain it...did it again, I think. Good thing I never tried to earn a living doing technical writing. I can see how I alarmed you if the reinforcement strip was making a big lump out of itself.

And now that you've rung the bell about the crossgrain reinforcement, I'm open to suggestion as to when I install it. Easier to do it all at once before the braces are installed, but then it needs to be carved away where the braces traverse. But installing it in pieces seems like that would be a recipe for unevenness of the back. Binary choice here, before or after braces? I think I'd like the reinforcement to be the first thing installed on the back, braces to follow, but this is my first solo trip on this task.

Thanks again.

I install it in one go against a straight edge. I then cut out channels for the braces. Given that it is cross grain and generally a soft wood, it is trivial to use a scalpel or an exacto to cut the strip. THen just clear with an appropriate chisel.

[peter havriluk]

John, thanks. I can see how chipping out the notches would be easier than five easy pieces...