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lyuv

Is tempering always a good thing?

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I need to make a metal cutting tool (a reamer). So it needs to be as hard as it can be. The question is: should I temper it after quenching?

The steels I have for the reamer are O1 and 5160. It's for a one time job, and needs to cut annealed steel.

Thanks,

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Yes. If you're reaming a hole in metal, you're putting some significant twisting force on the reamer itself, and a hardened but untempered tool could snap.

 

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If being used to cut annealed steel I would certainly temper the new tool to avoid brittle breakage.  The free online version of Machinery's Handbook will likely give you good guidance, but I don't have time to research it for you:  http://www.woodworkslibrary.com/repository/machinery_handbook_for_machine_shop_and_drafting_room_1914.pdf

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Thanks all.

Laticinno - that book is AMAZING!

G-son - First, I have never done this, so my plan is no more than hope. That said, the plan is to turn the reamer on a lathe to the general shape. Cut longitudonal grooves (with a Dremel), leaving several "blades". File the top of those blades at a slight relief angle, except for a narrow strip at the cutting edge. and finaly harden and sharpen with a stone.

 

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Serious question: given how much work is going into that, might it be a better use of your time and money to simply purchase a reamer? Or is what you want not available/too expensive where  you are?

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Yes the Machinery's Handbook has been around forever and was once an essential reference for any machinist, metal worker or mechanical engineer.  I think it has made it up to a 30th edition at this point, but I have an old hardcopy of the 14th, and the information within is still very relevant (particularly for low tech blacksmith work).

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3 hours ago, JHCC said:

Serious question: given how much work is going into that, might it be a better use of your time and money to simply purchase a reamer? Or is what you want not available/too expensive where  you are?

Two parts answer, and it too is serious:

1. Those of us that blacksmith for a hobby, could also find a more productive use for their time and money. But the chalange and the joy of making, are my (our?) reward. Same with the chalange of making a reamer.

2. The reamer is of special shape and not available. But it is needed for a project that is "only" for fun. So back to 1. :D

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A special shape? Any rotating cutter will make a round cut / hole. Are you using the wrong term for what you want to make?

Describe what you wish the tool to do or we can't be of much use to you. 

A reamer turns like a drill bit and can NOT make a "special" shape cut. Different diameter and depth, no problem. Different or "special shape? Nope, not a reamer.

Frosty The Lucky.

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Seen from above, certainly. However, lyuv might need to make a hole with a specific taper or unique counterbore. I'd still like to see a picture, though.

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Ayup but a taper is still a round cut. A reamer ONLY cuts one direction so there is ONLY that orientation that can be used to describe the reamer or results, looking down the length of the hole. Yes?  A reamer is a specific tool with specific results, I'm trying to determine what he actually wants to do so we can maybe help him. 

A fluted reamer is an exercise in grinding. It's not a beginner's exercise, even sharpening a reamer is an expert or automatic process, let alone making one. A reamer is NOT a trivial project. 

Frosty The Lucky.

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21 hours ago, Frosty said:

A reamer turns like a drill bit and can NOT make a "special" shape cut. Different diameter and depth, no problem. Different or "special shape? Nope, not a reamer.

Not all reamers are straight or plain tappers. Here is an example of a speciality reamer. Mine also has a radius thrown in...

 

Comb-reamer.jpg

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The answer to your question is yes, you need to temper. And there is a proper temper needed for this steel for your job. 

speaking generally, you may not want the temper to be the hardest, you may want a temper more suited for wear resistance.

Again generally, and i use this for O1, the hardest temper(light straw) is used for wood tools, not for removing steel.

If its too hard, your tool will chip

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