Tips for making things square/flat?

L

Leon Husock

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Jul 17, 2019
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I've been having real trouble making handle blocks square and flat, despite the fact that I've got a good variable speed Ameribrade grinder and a (non-variable speed) disc grinder. I had thought the problem was that I was putting uneven pressure on the material when grinding it, but even when I basically just let the block rest lightly on the belt it doesn't quite come out flat.

It's a problem because I'm trying to thin out and flatten non-metal frames for frame handles, and if they don't come out flat the scales won't be flush with the frame. If it were just flattening I could use a piece of plate glass and some sandpaper, but the thinnest I can slice material for frames is about 3/16" and I usually need to take them down to around .09". Any advice would be very much appreciated.
 
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Square, flat, and parallel are different beasts in the world of machining. For example you can set up a piece of steel in a vise that has .005 of taper built into it, and still cut a flat surface. The problem comes when you turn the steel over and try to machine a surface flat and parallel to the original.

For "flat enough" as in most knife making, I'd suggest a variable speed disc grinder. With practice it can be done. If you want to throw money at the problem, a SGA properly set up will do the trick. Contact cement, double sided tape, or a couple drops of CA glue will hold your parts to a piece of steel to grind them.
 
When I really care about things being flat, and square. I use a big marble tile (or whatever material it's made of) I bought at Lowe's. I grabbed a straight edge, and walked over to the flooring section, and checked a bunch of pieces to find something completely flat (don't just assume it will be flat). Brought the straight edge back to the section I got it from, and bought the piece I found. It was like 5 bucks.

Anyway, I get things as close as possible on the grinder, and get the rest done on that with some 80 grit 3m pro (cubitron 2). At least with my grinders, and discs. I havent been able to get anything perfect, but using this, I can.
 
Square means perpendicular in manufacturing and design engineering

I’ve made plenty of frame handles with silicone bronze and g10 at the thickness you mentioned.

Old reliable for me is a flat surface plate and sandpaper with a figure 8 motion.

You can try relieving the middle of whatever you are flattening to reduce the surface area that is in contact with whatever abrasive method you choose

But you say -“If it were just flattening I could use a piece of plate glass and some sandpaper,”.
So I believe you are saying you have trouble with the frame being parallel?
 

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HSC /// said:
But you say -“If it were just flattening I could use a piece of plate glass and some sandpaper,”.
So I believe you are saying you have trouble with the frame being parallel?
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Sorry, I realize I was being a bit unclear due to my inexperience with terminology. What I meant by that is I can get it flat by using a flat surface such as plate glass and some sandpaper to remove the bare minimum of material in order to make it flat, but I need to remove more material than that because I have to thin the frame considerably which would take a long time if I just hand sand the material away. It's possible I just need to try the plate glass/sandpaper method after grinding and use a coarser sandpaper than the 120 grit I've been using.
 
3/16 to .09 is a lot to remove…

I would buy the size I needed and or mill the frame stock down to the size I needed
 
HSC /// said:
3/16 to .09 is a lot to remove…

I would buy the size I needed and or mill the frame stock down to the size I needed
Click to expand...

I would but I'm working with my own stabilized wood for my frames. I've never tried stabilizing something like veneers where it's already 3/32" thick, but I have a feeling it'd warp like crazy. Honestly I'm thinking maybe it's just not a great system and I should go back to putting end cap bolsters with thin slots to hide the larger tang hole in the handle. I've been doing this for a couple years now and handles are consistently the part of my process I have the most difficulty/am the most dissatisfied with. Ah, well.
 
Keith Nix said:
Square, flat, and parallel are different beasts in the world of machining. For example you can set up a piece of steel in a vise that has .005 of taper built into it, and still cut a flat surface. The problem comes when you turn the steel over and try to machine a surface flat and parallel to the original.

For "flat enough" as in most knife making, I'd suggest a variable speed disc grinder. With practice it can be done. If you want to throw money at the problem, a SGA properly set up will do the trick. Contact cement, double sided tape, or a couple drops of CA glue will hold your parts to a piece of steel to grind them.
Click to expand...
double sided tape :)
Zx5NuCk.jpg

no tape , just two thick pieces of steel are enough to hold wood on place
41NAnla.jpg
 
Leon Husock said:
I've been having real trouble making handle blocks square and flat, despite the fact that I've got a good variable speed Ameribrade grinder and a (non-variable speed) disc grinder. I had thought the problem was that I was putting uneven pressure on the material when grinding it, but even when I basically just let the block rest lightly on the belt it doesn't quite come out flat.

It's a problem because I'm trying to thin out and flatten non-metal frames for frame handles, and if they don't come out flat the scales won't be flush with the frame. If it were just flattening I could use a piece of plate glass and some sandpaper, but the thinnest I can slice material for frames is about 3/16" and I usually need to take them down to around .09". Any advice would be very much appreciated.
Click to expand...
Do you have some pictures ?
I'm not sure I understand what you're doing and what problem you have? Many things can be done precisely on the disk , maybe i can help you with some idea how to do what you want to do ?
 
A few simple things make square and flat easier to attain.
Tram your rest/worktable on any tool to make sure it is flat. Many smaller rests/tables can be removed and lapped on a granite surface plate stone with 100 grit paper.
Make sure the worktable or rest is at the right angle to the grinder belt/disc. A $30 Wixey digital angle gauge is a good tool to have here. A good quality square is also nice.
You want everything square in all three planes.
 
HSC /// said:
3/16 to .09 is a lot to remove…

I would buy the size I needed and or mill the frame stock down to the size I needed
Click to expand...

I realized the effect I was looking for with the contrasting types of wood can be easily achieved while still using a thin metal frame by just putting two slices of wood on either side of the frame before adding the thicker scales, so the problem is solved (for now). Still, there's always another thing to make flat in knifemaking, so thanks everyone for the help!
 
My answer to this was to get a mini mill. I just could never get pieces both parallel (or square) and flat by hand….
 
Have a drill press? An end mill?
Dangerous as all get out.
 
Cushing H. said:
My answer to this was to get a mini mill. I just could never get pieces both parallel (or square) and flat by hand….
Click to expand...
Yep I totally agree here, it was the only way for me to get a perfect seamless fit between bolsters and the lower part of the scales
 
If we are talking Just handle materials wood/plastics....?

how about a little jig, and a plunge router?

that should be easy to plane (router) the heights you want that way.
 
Crag the Brewer said:
If we are talking Just handle materials wood/plastics....?

how about a little jig, and a plunge router?

that should be easy to plane (router) the heights you want that way.
Click to expand...
That's an interesting idea. I'd have to figure out how to make the jig, but I could definitely see that working.
 
Leon Husock said:
Another tool that's definitely on my short list.
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I never regretted getting one. What really drove me to it was wa handles with multiple sections on bolster and butt, where the flat/parallel thing really added up. But it is still really nice for single piece flat scales also. Also much better for drilling metal (either annealed or hardened)
 
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