Keeping things flat and parallel without a surface grinder?

C

Cubane

Well-Known Member
Hi everyone,

Since I am making folding knives it is pretty important to keep things flat and parallel. For my folders so far I have been using flat ground O1 so I haven't had to worry too much but I would like to start using some of the ATS-34 I have in them as well. The problem I have is how to get rid of the scale from the ATS-34 I have. The first thing I tried was on the flat platen on my grinder but that was pretty unsuccessful at both flatness and parallelism. I then got some surface ground at a local engineering shop but needless to say at workshop rates it is going to be rather expensive if I get that done each time I do an ATS-34 knife so I am looking for an alternative.

I don't have room for a surface grinder in my workshop or the cash to get one so that is out of the question. I do however have access to some parts to make a disc grinder. I was thinking of making a lapping machine or something that I can put the rough profiled blades into and get them nice and flat with the scale off them. I could also use it to flatten the liners as well rather than hand sanding them like I do at present. Whilst this will get them flat will it keep both sides of the blade parallel? it doesn't matter so much if the liners only have one side parallel but it is important for the blade to be flat and parallel. Any other ideas aside from buying a surface grinder? I could also use it for some damascus I forged as well and it would remove the need to buy flat ground steel giving me more options for steel types to use.

Edit: A lapping machine might also be useful for thinning down micarta etc for liner lock back spacers once I try out some more folders other than slip joints since they couldn't be done on a surface grinder anyway

Alistair
 
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To remove scale, even scale formed by forging which is much thicker than mill scale, I soak in distilled vinegar over night, then wire brush with a cup brush on a 4.5 inch angle grinder. It takes longer than the Muratic acid is the down side. The up side is you don't have to watch it as close (the vinegar will not damage the metal) and is much safer. You can dilute the acid but you must be sure and do it correctly, pour acid into water not water into acid. To keep this I think "Pour acid into water because if there is a splash you are more likely to have the water splash out rather than the concentrated acid". That is not really what happens, just how my mind keeps it straight. Actually pouring water into acid can cause of an out-of-control exothermic reaction. With which ever you use you need to neutralize with baking powder/water solution or some other base to prevent rusting. BTW also neutralize after etching with PCB (ferric-chloride) on damascus.

Check out this url, http://www.instructables.com/id/EFVWDTSLWYEV2Z8QB1/. I just ran up on it. This might be a good alternative to ferric-chloride, especially since it is getting harder to come by.
<);-)>
Wayne Coe
WayneCoe@Highland.net
http://www.WayneCoeBlacksmith.Etsy.com
423-628-6444
729 Peters Ford Road
Sunbright, Tennessee 37872
 
I've tried the vinegar approach before, but never anything stronger. The problem I am having with this sheet of ATS-34 is that it is very pitted so even when you think all the scale is gone I am still finding like black dots on the tang so I need to sand them down further (this is after getting them surface ground with instructions to get rid of all the scale) I had the same problem when sanding it down myself. I can do it by hand I guess just looking for a cheaper faster and more accurate solution if one exists. I saw in "Blade's guide to making knives" Allen Elishewitz uses a lapping machine to flatten his liners on one side so was thinking about options for one.
 
One other option is that if you have a small blade or area you want to keep flat it to rub it on a diamond shapener. It will show you areas that are not the same surface as the other steel.
 
Hmm the problem isn't really getting either side of the blade flat I can manage that without too many problems. It is more getting both flat sides parallel to each other. I guess when it comes down to it that is what a surface grinder is for really it is just a pity I don't have room for one. I'll have to do some investigation into a flat disc grinder and see what I can do with the parts I have. I am certainly not going to spend thousands on getting it surface ground at the local engineering shop it would be cheaper to throw that sheet away and buy all new flat ground stock.
 
Rusty McDonald said:
You can do it on a mill with the right jig or magnetic chuck.
Click to expand...

Can you explain more? I have a bench top milling machine so that could be the go. I am sure I could find a magnetic chuck to put on it. What do you use to grind it or would you just use an end mill or something to go over it?

Alistair
 
I was interested in the talk about "Shop Tours" posted by Indian George. I didn't find any forum or any heading like that so I clicked on "Search" then typed in Shop Tour. Up came several. Check out Les George's post (the second one). There are pictures of his surface grinder. If size is the issue this should solve it. How 'bout it Les? What brand is it, where do you get it, and is it expensive?

Maybe there could be a shop tour forum or heading (maybe there is and I just didn't see it). I would hope that this would just be for the makers to post their pictures and notes. People wanting to comment could do so elsewhere. This would just keep the tour cleaner.
 
Hmm a small one like that would be ok but I don't have the room. Already my grinder is on wheels and I wheel it out into the garage when I am doing some grinding and put it away so we can put the car in again. I think I'll try the end mill idea taking just a touch off at a time on a magnetic chuck and see how it goes. Will a magnetic chuck make the blade magnetic as well?
 
My surface grinder has a 6x12 fine pole magnetic chuck. It's a giant electro-magnet (?) that holds stuff down while you grind it, much the same as Jim's set up in a mill.

Jim is using grinding wheels, but you could use a fly cutter or endmill as already stated. The bigger the cutter, the fewer passes you will have to take.

No mater what tool you use to make things flat, you need to start out with a straight part first. if your part is warped and you put it on the magnet it will pull it straight and you will grind it flat. Then you release the magnet it will go back to bowed....

You should also take about the same off each side if possible. Ideally you should take a thou off and flip it over and take another thou, repeat as necessary.... Granted I never do that. I usualy have pretty good luck taking 4-5 thou off a side, flip and finish other side.

Who is getting me the double disk grinder for Christmas? :)
 
Bruce Barnett said:
Most fella's i know with milling machines would string you up if they found you using a grinder on their mill
Click to expand...

Why is that Bruce? as far as I can tell there wouldn't be much difference between a fly cutter and a grinding stone on there. That said when I inquired at the local industrial supplies shop they thought it was very dubious. Those cup grinding wheels are what they use to flatten cylinder heads at the place I am getting my steel surface ground and it is essential a drill press/milling machine type arrangement with a magnetic chuck underneath.

Alistair
 
Because grinding wheel fragments & metal dust & machine oil becomes grinding paste and gets into places on mills where it is not wanted!!!!!!!
 
Not true. magnet catches all the dust and the ways are covered. Been doing this for 7 years or better The only two surface grinders I have used had either a ruby grinding wheel and the other a 72 inch belt attachment. String me up if you wish Bruce, but don,t tie the knot till you see one working. I use boe lube so no build up of the nasty stuff you mentioned.
 
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