Lapping a plane sole

[bugbear]

Checked with a true straight edge

Call me a pedant, but how "true" is "true" ?

BugBear

 

[Benchwayze]

John, I agree, I find MDF fine.

If you use some kind of lubricant, do you seal the MDF with paint or varnish before lapping so that it doesnt get soggy?

Mike,
Use melamine faced MDF (I happened to get a piece of the white stuff, from an old kitchen.) Stick the wet and dry down with a spray on adhesive, and it's fine.

HTH
John

 

[Benchwayze]

Checked with a true straight edge

Call me a pedant, but how "true" is "true" ?

BugBear

Well BB, across both diagonals, my S/E showed the glass to have an inaccuracy the MDF didn't have, so I accepted it as true enough! But measuring it, it was rather more than the thickness of a few 'fag-papers' ccasion5:


Regards John

 

[bugbear]

Checked with a true straight edge

Call me a pedant, but how "true" is "true" ?

BugBear

Well BB, across both diagonals, my S/E showed the glass to have an inaccuracy the MDF didn't have, so I accepted it as true enough! But measuring it, it was rather more than the thickness of a few 'fag-papers' ccasion5:


Regards John

Sorry - I meant what was the specified tolerance of the straight edge.

BugBear

 

[custard]

Checked with a true straight edge, I found 18mm, melamine-veneered MDF to be flatter than float glass.

There's float glass and there's float glass. It's pretty common to find that it's "safety treated float glass", and the process they use for that often produces ripples.

 

[Benchwayze]

Hi Custard and BB

I must have had some of the rippled glass then Custard, so thanks for that info.

BB... I'll try to explain what I mean! ('Cos it isn't always what other people mean or believe! :wink: )

There was definitely a hollow across the diagonals. I suppose the gap was a bit less than 1/32nd" in old money. I don't have means to assess the straight edge to the n'th degree. I use it regularly around the shop and have never had cause to doubt it's accuracy (Or at least worry over how much).

I just found a discrepancy on the float glass but not on the Melamine faced MDF. (Nor along my planer-table as it happens.)

So, it's a bit like checking a spirit level. If it's accurate east to west, you turn it west to east. If the reading is the same, the level is good. (So my bricklaying friend told me years ago!)

Thus, if my straight edge rocks on one 'flat' surface but not on two others then I don't blame the straight edge. As I said, it serves me well.

Since I bought thicker blades for my Stanleys and one or two LN planes, I have reverted to honing without a guide, on a water stone. I use wet 'n dry on a flat surface only for lapping. The results are well within the tolerances that are really needed for woodwork. Although there will be those who disagree on that point.

I have always worked as accurately as I can, realising that the material we use moves over time. To my mind, this defeats the object of working to 'engineering tolerances' in wood. That's not to say I work sloppily, or beat a joint together 'til it screams. (hammer)

Cheers
John

 

[Woodmagnet]

Checked with a true straight edge

Call me a pedant, but how "true" is "true" ?

BugBear

"You're a pedant" :lol: :lol: :lol:

 

[bugbear]

So, it's a bit like checking a spirit level. If it's accurate east to west, you turn it west to east. If the reading is the same, the level is good. (So my bricklaying friend told me years ago!)

It may mean the spirit level is insensitive (*)!

BugBear

* which is easily checked for, if course

 

[Benchwayze]

So, it's a bit like checking a spirit level. If it's accurate east to west, you turn it west to east. If the reading is the same, the level is good. (So my bricklaying friend told me years ago!)

It may mean the spirit level is insensitive (*)!

BugBear

* which is easily checked for, if course

Or that my house is slowly leaning! ccasion5:
John