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View Full Version : Tool Steel ??????



JoeLee
05-31-2012, 01:22 PM
I have to make some threaded t-bolts which have to be hardened, my first choice was 01 since I have plenty of it in the shop. The problem is it threads like hot rolled weather I thread it with a die or single point it in the machine. (ripped up looking threads) it's just the nature of the material. Is there a different tool steel that has better machining charcteristics that any one has used???? like W1 maybe???

JL...................

Dr Stan
05-31-2012, 02:18 PM
Personally I would not use any tool steel, but something like 4130, 4340, 8620, or similar material. You actually want a hard exterior and a relatively soft interior so the head will be less likely to break off when tightened.

RWO
05-31-2012, 04:28 PM
O1 typically gives rough threads with a conventional die in my experience.
4140 would be my choice because it machines nicely and can be heat treated to RC 38-40 easily enough. This gives ample hardness and good ductility.

RWO

goose
05-31-2012, 05:01 PM
I've had pretty good results with O1, chasing the threads with a die after single pointing. Nicely formed, fairly smooth, with a little fuzz that may need sanding. W1 steel I found knarling to thread with decrepit furry threads.
Alloys like 4140 thread quite well; smooth, silky threads.

Black_Moons
05-31-2012, 05:44 PM
Can I ask: Why does it need to be hardened?

gwilson
05-31-2012, 06:51 PM
I have found that even drawn to a blue color after hardening,screws tend to be too brittle from 01. I agree with Stan about metal selection.

saltmine
05-31-2012, 07:00 PM
I don't have any problem machining O-1 drill rod. In fact, I just had to replace the shaft on one of my QC tool posts (the clamping lever)
I cut it to the correct major diameter with and HSS tool bit, and threaded it with a good quality die. No, the threads look fine. But, I have noticed that improperly sharpened or dull tool bits have a tendency to make rough looking cuts on O-1 metal. Sometimes I revert to HSS because carbide doesn't finish that well on it either. A dull or worn die is something I usually throw away instead of putting it back in the set.

JoeLee
05-31-2012, 08:56 PM
I used a new threading insert at about .005 per pass. Being done on a tool room lathe I have little other choice other than to cut in back gear. Maybe the speed has something to do with the finish as well as it just being a characteristic of the material. The picture doesn't show it but the infeed side of the threads are tore up, pretty ugly. I also tried turning to within .010 of finish dimension and chasing it out with a new die but the results are the same. The original bolt, the blued one is hard..... can't scratch it with a file so it's hard. Maybe it's a different material, I might try the 4140 and see what type of finish I get with that.
I usually have good luck turning 01, a little fuzzy as mentioned but not tore up. I haven't tried a HSS tool bit but I suspect the result would be the same.

JL....................

http://i911.photobucket.com/albums/ac317/JoeLee09/Aloris%20Tool%20Holders/Image009.jpg
http://i911.photobucket.com/albums/ac317/JoeLee09/Aloris%20Tool%20Holders/Image010.jpg

bob_s
05-31-2012, 09:18 PM
Consider using aisi 1151 steel.

Free machining steel can be hardened to HRC 55 if that's what you want.

cameron
05-31-2012, 10:46 PM
If you can't scratch the original bolt with a file, I would expect that it is case-hardened.

oldtiffie
05-31-2012, 11:12 PM
I have to make some threaded t-bolts which have to be hardened, my first choice was 01 since I have plenty of it in the shop. The problem is it threads like hot rolled weather I thread it with a die or single point it in the machine. (ripped up looking threads) it's just the nature of the material. Is there a different tool steel that has better machining charcteristics that any one has used???? like W1 maybe???

JL...................

I am a little curious as to why t-bolts are used when ordinarily ex-stock t-nuts and a high-tensile bolts will suffice.

Jaakko Fagerlund
06-01-2012, 12:56 AM
If you can't scratch the original bolt with a file, I would expect that it is case-hardened.
Maybe, but the threads would quickly strip out because of that. Other option is that the surface may have a shallow nitriding, this doesn't cut with a file at all (slippery).

kd4gij
06-01-2012, 01:56 AM
Try leaving it a little over size and cleaning it up with a good thread file. Works for me.

JoeLee
06-01-2012, 08:52 AM
I think the original one was something other than 01, it's not case hardened or nitride coated. These are used on a grinder so I would imaging they were hardened for wear.
If I used say 1151 which you say can be hardened up to HRC 55 which would be perfect, would that be oil quench and done?????? no drawing it back etc.
I never used that material before, don't even know if I can find it.

JL................

bob_s
06-01-2012, 03:43 PM
If I used say 1151 which you say can be hardened up to HRC 55 which would be perfect, would that be oil quench and done?????? no drawing it back etc.


Sorry but no. Water or brine quench for anything larger than 1/4" diameter, then temper at 400F for 1 hour per inch of thickness, and slow cool, no more than 28F per minute?, to room temperature

1151 is very similar to 1144, but with higher carbon content. Heat treatment (hardenability bands are similar, again the higher carbon content allows for higher hardness)

If you want single step heat treatment, you can go with, as Dr Stan mentioned, 4340H, and live with the lower machinability. So machine as required, heat to austenizing temperature and air cool.

Duffy
06-01-2012, 10:26 PM
Joe, why could you not turn down a large grade 8 bolt to the correct head and shaft size and thread it? Grade 8 bolts are certainly tough and, while not VERY hard, they should give reasonable service. Since there would only be the machining stage, making more would be no problem.

Jaakko Fagerlund
06-02-2012, 03:52 AM
These are used on a grinder so I would imaging they were hardened for wear.
99% chance they are not in any way different than maybe by dimensions from regular bolts.

Where exactly are they used or for what? I've seen plenty of grinders and all of tehm use off-the-shelf components.