# home built cutter, steel type?



## LEEQ (Dec 8, 2013)

So I'm contemplating making single tooth cutters for gear cutting on the mill. The toughest material they will probably be cutting is mild steel. I will be doing a caveman heat treat job. Like heat to straw yellow then quench in oil. No fancy equipment. They take the form of 1/4" square bar. I am getting a bit overwhelmed in the selection of steel for the cutters. I found a listing of tool steel that included 1018. The same outfit had 1018 bar stock listed in cold formed at a considerable savings. Are they different end products despite being the same alloy? Is either one suitable for a cutter shaped like the space between teeth and spun around impacting and cutting steel once per revolution? I'm new to tool type steel and need some help. What should I be looking for?


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## dave2176 (Dec 8, 2013)

1018 would be a poor choice. It doesn't harden well or much. For your oil quench you would use O-1 which is commonly drill rod. Any reason you couldn't use a high speed steel bit that is already hardened? Just grind it, insert it and go to work.

Dave


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## LEEQ (Dec 8, 2013)

Lathe bits ground sound like much less trouble, I'm not sure how I would duplicate this by grinding though. Not in my limited shop. I plan on reaching the proper geometry with some math and certain sized end mill to achieve certain radius at a certain place on the bit. I know this works, so I'm not changing the bit design.  I might be able to anneal some old drill bits and use those.


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## iron man (Dec 9, 2013)

We use to use a lathe bit as a single (fly) cutter for gear teeth all the time it is slower but works well. Ray


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## LEEQ (Dec 9, 2013)

Did you grind the profile?


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## David Kirtley (Dec 11, 2013)

O1 drill rod (and you can get it in flat as well.) 

Relatively cheap, readily available, and easy to work with. Hardening and tempering it is harder to describe than to do. Quench it in oil and toss it in the easy bake oven for a while to temper. It is pretty forgiving. Another approach is hobbing gears (assuming that they are spur gears but you can also hobb worm gears) Hobbynut had a series on making them on youtube and Jose Rodriguez has a video that you can buy through LMS.

The real advantage to using O1 over HSS is that in it's annealed state, it is much easier to work. Just patience and files and you can make whatever shape you want.


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## iron man (Dec 12, 2013)

LEEQ said:


> Did you grind the profile?



yes we did it is pretty easy.


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## LEEQ (Dec 12, 2013)

At this point I don't want to hob just yet. I will get some 01 or similar tool steel if I have to, but I'm not finding much in the way of decent prices on 3/16" or 1/4" square. Do you guys know what regular old drill bits are made of? I'm pretty sure I can find free old bits and anneal them in the coals of a wood fire. I would have to figure their steel type so I could find the proper heat treatment though. Could you tell me how you did that grind job? Any pics or description would be great. I might take that 1018 1/4" square and piddle. I just have a 6" grinder with fairly fine wheels. One advantage of the method I had in mind, would be repeatability. I could sharpen both ends of a few bits while I was set up and know I cold swap out midway through a 47 tooth gear if I found myself in need. I don't know about my ability to freehand two bits the same.


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## iron man (Dec 12, 2013)

LEEQ said:


> At this point I don't want to hob just yet. I will get some 01 or similar tool steel if I have to, but I'm not finding much in the way of decent prices on 3/16" or 1/4" square. Do you guys know what regular old drill bits are made of? I'm pretty sure I can find free old bits and anneal them in the coals of a wood fire. I would have to figure their steel type so I could find the proper heat treatment though. Could you tell me how you did that grind job? Any pics or description would be great. I might take that 1018 1/4" square and piddle. I just have a 6" grinder with fairly fine wheels. One advantage of the method I had in mind, would be repeatability. I could sharpen both ends of a few bits while I was set up and know I cold swap out midway through a 47 tooth gear if I found myself in need. I don't know about my ability to freehand two bits the same.




 I think your over thinking this we hand ground a lathe bit to fit the gear we where making, if we where starting from scratch we would find a gear with the same tooth and hand grind the tool bit on a bench grinder to fit that gear. Most of the time we would grind two or three in case of a crash but a regular lathe bit is good enough I would look no further than that. Just take your time and grind it till it fits the space inbetween the gear teeth just like you would when cutting theads. It really is not any differant than sharpening a tool bit to cut an ACME thread.. Ray


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## savarin (Dec 12, 2013)

http://www.hobby-machinist.com/showthread.php/10122-tumbler-reverse
I'm a total newb with zero training but managed to cut a gear with a bit ground by eye.
Full story in the link.


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## iron man (Dec 13, 2013)

savarin said:


> http://www.hobby-machinist.com/showthread.php/10122-tumbler-reverse
> I'm a total newb with zero training but managed to cut a gear with a bit ground by eye.
> Full story in the link.



Now that is very creative!!


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## LEEQ (Dec 13, 2013)

So did you ever recut that gear in steel and work out how it meshed in reverse? I'm curious as to how all that came out. I was hoping to avoid ironing out those difficulties by following a set of carefully lined out specs. The method calls for using a certain sized endmill brought in to a certain distance from the bit in the x and y on the mill. I suppose instead of an endmill I could turn something that fit in a collet on one end and fit the endmill diameter on the other. I would then rough grind the bit, put it in the fixture and apply abrasive paste to the hardened, turned tool in the spindle. That way I could use the hss I have for bits. I could avoid buying some mills and collets also. I've not done any lapping/cutting like this before, but I think it might work. Free drill bits still sound good for the cutter- cutter. Does anyone know how to determine the steel type of drill bits?


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## savarin (Dec 13, 2013)

LEEQ said:


> So did you ever recut that gear in steel and work out how it meshed in reverse?



No, too busy with other stuff but its still working fine. I've cut a left hand 8mm thread and used the saddle feed in reverse with no problems other than the slight difference in sound in reverse but you have to listen really well to hear it, the out of round 120/127 make far more noise.



iron man said:


> Now that is very creative!!


Thanks, I learnt so much from that exercise its incalculable.


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## iron man (Dec 13, 2013)

There High speed steel same as a lathe bit but they are hardened different. Your making gear cutting far to critical there is a fair amount clearance in any gear and even if they are not perfect after they run a while they find there spot and break in just fine. Ray


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## LEEQ (Dec 13, 2013)

iron man said:


> There High speed steel same as a lathe bit but they are hardened different. Your making gear cutting far to critical there is a fair amount clearance in any gear and even if they are not perfect after they run a while they find there spot and break in just fine. Ray



Firstly, I totally admit to being anal about things. I tend to do them my way, probably taking longer than necessary to do about everything I've ever done. I've only had one unsatisfied customer in 22 years. You can't please every one, but I've come pretty close. Every other customer has appreciated my attention to detail. I know my way is often slower, but I'm proud of my work. I like this hobby and am trying to learn deeper than just the field expedient method to get 'er done. Two of these gears  will be steel meshing with plastic. I don't want them chewing because I was off a bit. Thank you all for your advice on methods. I steal tricks when I see a good one, and there are tons here.      Secondly Thanks for the steel advice. That's really my main question here and any help I get is much appreciated. I'll search around a bit for methods of annealing and heat treating hss. I have not done much of that and am definitely interested. There are always future projects to apply these lessons to.     Lastly, are pretty much all regular old twist drills hss?

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savarin said:


> No, too busy with other stuff but its still working fine. I've cut a left hand 8mm thread and used the saddle feed in reverse with no problems other than the slight difference in sound in reverse but you have to listen really well to hear it, the out of round 120/127 make far more noise.
> 
> 
> Thanks, I learnt so much from that exercise its incalculable.



Good to hear that worked out for you! I'm a rank amateur and am encouraged by your success.


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## LEEQ (Dec 14, 2013)

well, it appears annealing hss is probably out of my range. Pooey. Guess it won't be of annealed and treated hss. Perhaps just some O1. Got an odd piece of D2 layin' around. I wanted something in the way of square stock, though. I guess you have to pay for what you want sometimes.


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## george wilson (Dec 20, 2013)

actually,gears made wrong won't wear in,they will wear out.

To make any hardened tooling you first must get a knowledge of tool steels and how to harden and draw them. There are any number of books on the subject.

I would caution you that even 01 is not a great choice for making gear teeth. There are many teeth on a gear of any size at all. You cannot stop cutting gear teeth part of the way through to remove the cutter and sharpen it. Even just sharpening it without removing it will cause the cutter to be a little shorter,and perhaps a little smaller,depending upon how you ground it.

Clock makers in the old days made brass gears with a single tooth cutter,but those clock gears were brass,and they were very narrow. Much easier on the cutting tool.

I would encourage you to at least try to learn how to grind a HSS lathe tool to an accurate profile. You can carefully grind them on the corner of a wheel,and finish them with a small grinding point and a Dremel type tool.


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## LEEQ (Dec 20, 2013)

george wilson said:


> actually,gears made wrong won't wear in,they will wear out.
> 
> To make any hardened tooling you first must get a knowledge of tool steels and how to harden and draw them. There are any number of books on the subject.
> 
> ...



I was hoping to use a careful, precise set up to make a few double ended bits up to the same specs. By doing so I believe I can set up a job to make changing bits mid job possible. Is there a better steel for such a single point cutter that I can heat treat/temper at home? I know this works, a respected author gave me his method and spec's. Unfortunately being foreign he is not at all familiar with our steel labeling. This leaves me hunting an appropriate choice of steel. One more question for you. Do you think a hss cutter can do 50 teeth in mild or carbon steel? Thanks for the help/ pointers


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