Thread: Waterstone problem

That would be the case in lapping ... where two surfaces come to conform to each other ... but if the two materials can be made to move in parallel to each other (regardless of the mating surfaces) then any material at the interface that is out of parallel has to be removed. (I'm not sure if that is what is going on in flat honing (Flat honing - Wikipedia, the free encyclopedia))

As I said, it's kinda theoretical ... but I know that two highly wonky oilstones can be rubbed together to get them both flat - so I think it applies in practise also. That's the picture I have in mind when I think of it - the high points of both surfaces coming off first, then increasing flat sections appearing ...

Cheers,
Paul

Does this not presuppose that you were always rubbing the two stones together in the precisely the same direction?

I was lapping/flattening rock slabs last summer (fine sand & water). My best results were random orbits of one stone on another. The diamond band saw was clearly "jumpy", leaving +/- 1mm ridges maybe 3cm wide. This is a saw with 8' wheels and a diamond rope for a blade. I can drive my 3/4 ton GMC Suburban through the rock cradle. Right angles, diagonals, offset parallels, the different directions all helped.

As I said, it's kinda theoretical ... but I know that two highly wonky oilstones can be rubbed together to get them both flat - so I think it applies in practise also.

Paul, my mind boggles how you would do this in practice! Let's say that this one should stay in the "Theoretical" file!

Regards from Perth

Derek

Originally Posted by pmcgee

As I said, it's kinda theoretical ... but I know that two highly wonky oilstones can be rubbed together to get them both flat - so I think it applies in practise also. That's the picture I have in mind when I think of it - the high points of both surfaces coming off first, then increasing flat sections appearing ...

Dunno about that theory... given that you hand-grind glass lenses by rubbing two flat disks of glass together!

Originally Posted by Robson Valley

Does this not presuppose that you were always rubbing the two stones together in the precisely the same direction?

RV - you picked up a flaw I realised while I was at work.
Each line of interface between the two materials - in the axis of motion - would be made parallel to that axis of movement, but it wouldn't guarantee that all the lines across the surface were level across the width.

Introducing other motions I think solves that issue ... the flat honing link mentions movements like a spirograph drawing.


Derek ... I only mention it because it was the second method of flattening I ever used ... the first was a foot square piece of limestone paving. And they both worked. So, as a result I've had the theory in the back of my mind for a couple of years that if both surfaces wear at about the same rate, then maybe you can flatten just about anything with just about anything.

I'll try and do a quick experiment and put it in the blog section - I don't want to steer this conversation off the rails.

Cheers,
Paul

PS - someone I was reading recently said Krenov (or Frid?) wasn't fanatical about flat stones. Some of the oilstones you see make me wonder who by and how these were used.

honing 002.jpg

PPS: Ok ... I kinda shutoff the braincells when I started this ... so I'm pleading "up since midnight"
https://www.woodworkforums.com/blogs/...erimental-932/
It might lend some weight to my musings ... I'll have another go at it when I can ...

You have to be obsessive about flatness if you're rehabbing a bench chisel or plane blade.

To get a good edge the back has to be flattened and polished.

A poofteenth out on one grit will mean the next has to do more than double the work.

Hi,
A coarse diamond plate has an additional benifit of being able to be held under a running tap and it really flattens the stone fast when used this way. If you do not want to change to flattening with a diamond plate try a coarser grit like 120g, the resulting fine scratches on the water stone do not hinder its ability to sharpen to the specified grit but may make the metal removal a little faster.

I flatten my water stones at the end of each sharpening session so they are ready for next time, and if a lot of sharpening is undertaken I will even flatten them during the session. That way there is a fresh exposed cutting surface that is much freer cutting than one that may be clogged with very fine crud due to infrequent flattening.

Also some wet stones do not like being left in water perminantly and may get fungus and algae growing in the pores of the stone.

I have noticed that some brands of water stones do not clear the cut metal and crud as well as others. I once tried a bit of dish detergent in the water with very little improvement. Then I read about people in the US using a general purpose cleaner called "Simple Green" as a 50/50 mix in water. I found Bunnings sold it in a trigger spray bottle for around $5. The stones were immediately visibly cleaner and cut far faster with this simple green mix. I have been using it ever since on all sharpening stones, water, diamond and ceramic. I also use about 10 -15% of it in the bath of my Tormek wet stone sharpener. Great stuff, it may help your problem.