Reaming holes before or after hardening

[Jeroen Beskers]

Im currently working on a balisong trainer. I have my titanium handles fit and reamed and I can lathe my own bushings/washers. Was planning to get started on the blades but wondered if I need to ream the holes before or after hardening. Do I need to buy better reamers so I can ream after hardening? The steel I am using is Sandvik 12c27 and I also have hardening foil so the blade will stay clean. The stock is 4 mm (0,157 inch) thick. The lathe I have at home is not biggest or best but I can make it work.
Btw, i am from the Netherlands so I only use metric tools and buying from America is really expensive for me(yet).
A quick sidenote. Is it possible with this too harden in oil or is it a must that I harden this between aluminium plates. I think oil wont be a problem since they are trainers and thus are more thick. Il harden this all in my electric hardening oven so the temp is not a problem

Greetings
Beskers Bladeworks

 

[Stacy E. Apelt - Bladesmith]

I would quench in oil and then immediately place in the aluminum plates. This will keep warp down. After a minute in the plates, place in a dry ice slurry, or a very cold freezer. Then temper twice.

Carbide reamers can be used post-HT. They will last many times longer and are worth the extra cost. Best method is to ream before HT and the second reaming after HT will be just a quick clean up pass.

 

[Scaniaman]

Sandvik says oil-quench on their homepage. Your blade is pretty thick, and I guess not too long. So the warp preventing part of plate quench may not be of importance to you...

 

[Jeroen Beskers]

I would quench in oil and then immediately place in the aluminum plates. This will keep warp down. After a minute in the plates, place in a dry ice slurry, or a very cold freezer. Then temper twice.

Carbide reamers can be used post-HT. They will last many times longer and are worth the extra cost. Best method is to ream before HT and the second reaming after HT will be just a quick clean up pass.

Thanks. I think il put it in a freezer. I wonder tho if the aluminium plates are needed since its thick stock and the blade are trainers so no grinds on them. Or just a fake edge for show. I already have a carbide reamer I think.

 

[Jeroen Beskers]

Sandvik says oil-quench on their homepage. Your blade is pretty thick, and I guess not too long. So the warp preventing part of plate quench may not be of importance to you...

thanks
Its 12 cm total. And since its a trainer it doesn't have a grind. Only a few holes. Maybe il put a grind on some but the edge will still be 2 mm thich.

 

[Scaniaman]

To be extra safe and straight I guess you could do what Stacy above suggest. But I don't think you have to use aluminium, you already quenched in oil. Any thick hard straight piece of metal would do. 5mm thick mild steel angle bar? Place blade spine down between two pieces and squeeze together with a couple of clamps.

I quench that way between two 50x60x5000 mm aluminium blocks with a couple of 600 kg Bessey clamps.

I go a little overkill (?) on chefs and after the quench I put the blade between two 5mm thick aluminium angle bars tightly squeezed with c-clamps and keep the blade there all through freezing and tempering. My last 210 mm chef from 14C28N came out dead straight. This pic only shows 2 clamps, I use three, evenly distrubuted.

I grind a little pre heat treat but always keep a flat part along almost the entire blade so that I can keep it straight in the quench.

 

[JTknives]

Holes WILL chance diameter after heat treating. Any tight tolerance holes should be carbide reamed after heat treat.

 

[Drew Riley]

Another option is to ream pre-heat treat, and then clean out the hole with a barrel lap post heat treat.

 

[Jeroen Beskers]

Another option is to ream pre-heat treat, and then clean out the hole with a barrel lap post heat treat.

How much does such a tool cost? and if you know by any chance is this available in the eu.

 

[Jeroen Beskers]

To be extra safe and straight I guess you could do what Stacy above suggest. But I don't think you have to use aluminium, you already quenched in oil. Any thick hard straight piece of metal would do. 5mm thick mild steel angle bar? Place blade spine down between two pieces and squeeze together with a couple of clamps.

I quench that way between two 50x60x5000 mm aluminium blocks with a couple of 600 kg Bessey clamps.

I go a little overkill (?) on chefs and after the quench I put the blade between two 5mm thick aluminium angle bars tightly squeezed with c-clamps and keep the blade there all through freezing and tempering. My last 210 mm chef from 14C28N came out dead straight. This pic only shows 2 clamps, I use three, evenly distrubuted.

I grind a little pre heat treat but always keep a flat part along almost the entire blade so that I can keep it straight in the quench.

Il probably use this to keep it straight. Thanks

 

[Jeroen Beskers]

Holes WILL chance diameter after heat treating. Any tight tolerance holes should be carbide reamed after heat treat.

So drill before hardening and after the treatment ream it?

 

[Drew Riley]

How much does such a tool cost? and if you know by any chance is this available in the eu.

Here in the states, a 1/4” lap will run about $10-$15. The lapping compound is usually around $15 to $20ish for a small jar depending on grit type and size. I imagine it’s available all over the world. Most industrial supplies should have them.

 

[12345678910]

Are you intending to put bushings in the reamed hole ?

If you drill, harden, then press in the bronze bushings (which makes it replaceable for wear)

Then ream the bushing final hole size with cheap simple HSS reamer.

But then your hole sizes have to be somewhat larger to make up for the bushing thickness.

 

[Busto]

Lapping is a final abrasive finishing operation that produces extreme dimensional accuracy, corrects minor imperfections, refines surface finish and produces close fit between mating surfaces.
For SMOOTH Flipping this would be the final finishing step to ensure the Hole tolerance is clean and free of any burrs.

 

[Jeroen Beskers]

Are you intending to put bushings in the reamed hole ?

If you drill, harden, then press in the bronze bushings (which makes it replaceable for wear)

Then ream the bushing final hole size with cheap simple HSS reamer.

But then your hole sizes have to be somewhat larger to make up for the bushing thickness.

Im planning to use bushings with washings on these trainers. Il be making these myself since ive got a lathe at home.

 

[Jeroen Beskers]

Here in the states, a 1/4” lap will run about $10-$15. The lapping compound is usually around $15 to $20ish for a small jar depending on grit type and size. I imagine it’s available all over the world. Most industrial supplies should have them.

Thank you. Do you know any names or brands I can search for. Or how the tool is called exactly. Because I cant find them in the eu yet.
Thanks

 

[Jeroen Beskers]

Lapping is a final abrasive finishing operation that produces extreme dimensional accuracy, corrects minor imperfections, refines surface finish and produces close fit between mating surfaces.
For SMOOTH Flipping this would be the final finishing step to ensure the Hole tolerance is clean and free of any burrs.

When would you lap the blade. Ream, harden, ream and then start lapping or drill a hole, harden it and lap it?

 

[DAMNENG]

Im currently working on a balisong trainer. I have my titanium handles fit and reamed and I can lathe my own bushings/washers. Was planning to get started on the blades but wondered if I need to ream the holes before or after hardening. Do I need to buy better reamers so I can ream after hardening? The steel I am using is Sandvik 12c27 and I also have hardening foil so the blade will stay clean. The stock is 4 mm (0,157 inch) thick. The lathe I have at home is not biggest or best but I can make it work.
Btw, i am from the Netherlands so I only use metric tools and buying from America is really expensive for me(yet).
A quick sidenote. Is it possible with this too harden in oil or is it a must that I harden this between aluminium plates. I think oil wont be a problem since they are trainers and thus are more thick. Il harden this all in my electric hardening oven so the temp is not a problem

Greetings
Beskers Bladeworks

Jeroen
Since as you stated this knife is a trainer, which will not have an edge and will not be used to cut, why are you hardening it?
Jim A.

 

[Jeroen Beskers]

Jeroen
Since as you stated this knife is a trainer, which will not have an edge and will not be used to cut, why are you hardening it?
Jim A.

Hey
You indeed have bali trainers with an unhardened blad and with an hardened blade. They harden the blade so it wont bend as fast during the dropping which could collide with the handles.
Jeroen Beskers

 

[Drew Riley]

Thank you. Do you know any names or brands I can search for. Or how the tool is called exactly. Because I cant find them in the eu yet.
Thanks

The only brand name I usually see is "Acro" or "acrolap", though I'm sure there are more out there. Normally they're just called a "barrel lap", thought I've also seen "cylinder lap". Maybe somebody from your neck of the woods can chime in, but you may just have to find a US based suppler that ships internationally? Maybe try searching eBay or Amazon as well.