Cutting Carbon Steel Shafting

[firworks]

For a project I'm working on I need a ~2" long 1/4" shaft to fit into a bronze bushing. I bought a 12" shaft and figured I'd cut it with my M12 bandsaw no problemo. The shaft was a Thomson Quick Shaft, Class L, Carbon Steel 60 Rockwell C type. I've cut all kinds of stuff with my M12 bandsaw before with ease. After 10 minutes of trying here I had a tiny nick in this shaft... I see now that's not going to work. What would be a good way to cut this for a DIYer type in a home shop? I was going to try a cut off disc in my angle grinder next. I don't have an abrasive chop saw or I'd be trying that instead.

One other question is: Am I asking for some kind of terrible chemical reaction using this shaft in a bronze bushing? While I was prototyping I left the shaft sitting in the bushing and it looks like the whole contact surface was orange with surface rust or some other kind of reaction. Was that just from the surface of the shaft wearing out from abrasion against the bushing or can I not use bronze bushings with carbon steel shaft/whatever coating/plating they are putting on it?

 

[Rookie2]

1/16" or 1/8" abrasive cut off wheel in your angle grinder will do just about any shaft. I wouldn't think you'd have any worries using bronze with carbon steel.

 

[larry_g]

The old machinist that I worked with refereed to Thompson shafting as "Harder than a whores heart." You will need an abrasive cutoff wheel to cut that.

lg
no neat sig line

 

[csp]

x2 on the angle grinder/cutoff wheel

 

[manwithtools]

One other question is: Am I asking for some kind of terrible chemical reaction using this shaft in a bronze bushing? While I was prototyping I left the shaft sitting in the bushing and it looks like the whole contact surface was orange with surface rust or some other kind of reaction. Was that just from the surface of the shaft wearing out from abrasion against the bushing or can I not use bronze bushings with carbon steel shaft/whatever coating/plating they are putting on it?

I think you answered your own question. It was "sitting in the bushing" - no wear occured there. The discoloration could be for multiple reasons. Bronze bushings and a hardened shaft are fully compatible. Carbon Steel has little to do with the difficulty in cutting the shafting, 60 Rockwell does. Do a search on Rockwell hardness and I think you will be more knowledgeable about metal hardness and the required tools to work with this shafting.

As a buddy used to say "that Sh** is harder than woodpecker lips"

Abrasive wheel is your ticket.

 

[no704]

Just use a dowel pin?

 

[larry_g]

Just use a dowel pin?

Dowel pins run over size by up to .0005" where as Thompson shafting is .0005 to .001" undersize. So bearing clearances come into play here. One may work and the other may not being there is up to .0015" inch difference.

lg
no neat sig line

 

[no704]

Learned something new today. Thanks!

 

[Know Wosad]

Yeah. A good bandsaw blade might be about the same hardness as the shaft. No workie.
Pure carbide will cut it in a lathe or horizontal mill, no problem. I might go after it with the Ceremet in my Makita dry chop saw but the $ isn't worth damaging that blade either.
Cut it slow with the abrasive. Cut a little and let it cool a bit. Dont heat it until it turns blue. You could alter the temper.....who knows what kind of steel it is. My guess is 4140 HT but there's no telling. A2 or D2 could get strange with too much heat(air hardening steels) Just take it easy and make a straight cut with a disk.It may only be surface hard like a shock absorber or cycle fork. Score it all the way around with the abrasive then go after it with the bandsaw or a hand hacksaw again just for the hell of it.It may be just surface hard..Prolly is.

 

[HammerMechanic]

Thomson 60 Shafts are case hardened, but being it is only 1/4" diameter you will be through it in seconds with a cut off wheel in angle grinder.

 

[HammerMechanic]

Plus cutting carbon steel is easy. What is far more important here is exactly what manwithtools said - it is case hardened to 60 Rc. So your thread title would be better served saying Cutting Case Hardened Shafting.

 

[firworks]

I think you answered your own question. It was "sitting in the bushing" - no wear occured there. The discoloration could be for multiple reasons. Bronze bushings and a hardened shaft are fully compatible. Carbon Steel has little to do with the difficulty in cutting the shafting, 60 Rockwell does. Do a search on Rockwell hardness and I think you will be more knowledgeable about metal hardness and the required tools to work with this shafting.

As a buddy used to say "that Sh** is harder than woodpecker lips"

Abrasive wheel is your ticket.

Well, I was playing with it spinning it quite a bit so I wasn't sure if it was some of the bushing that had worn off on the shaft or if the shaft had some protective coating worn off. It does look ugly like rust but it still spins silky smooth.

Thomson 60 Shafts are case hardened, but being it is only 1/4" diameter you will be through it in seconds with a cut off wheel in angle grinder.

Yep, the angle grinder went through it like a hot damn! I cleaned up the cut on my stationary belt sander.

Thanks for the information everybody. This thing spins great!

https://twitter.com/firworksyt/status/765940269426548736

Also I didn't realize you have to record video for Twitter vertical so it's a horizontal video framed vertically.

 

[larry_g]

...who knows what kind of steel it is. My guess is 4140 HT but there's no telling. A2 or D2 could get strange with too much heat(air hardening steels) Just take it easy and make a straight cut with a disk.It may only be surface hard like a shock absorber or cycle fork. Score it all the way around with the abrasive then go after it with the bandsaw or a hand hacksaw again just for the hell of it.It may be just surface hard..Prolly is.

http://www.thomsonlinear.com/downloads/bearings_guides/RoundRail_LinearGuides_Components_cten.pdf

Thompson shafting is well know and defined in the industrial setting. The above link will give you way more than you may want to know, including cutting instructions, pg 277.

lg
no neat sig line

 

[bullnerd]

If you don't have a chop wheel, you can bench grind around the outside and snap it by hand.

 

[duc916]

As a note for future projects, you can order undersized dowel pins. Larry G is correct that standard dowel pins have a + tolerance zone, but undersized dowel pins are +0 / -0.0002 (in 1/4" size). You can also order oversized dowel pins if your hole is a little too large. All three versions are pretty common, you can get them from McMaster Carr.

 

[dadsEH]

Cut off wheel.....end of story.

 

[csp]

Yep, the angle grinder went through it like a hot damn! I cleaned up the cut on my stationary belt sander.

For those not keeping up, the OP has already made the cut.

 

[bullnerd]

Also....you could take an old hacksaw blade and braze small pieces of carbide to every other tooth, then.....

 

[OccupantRJ]

Bronze sometimes is not the best for the type of bushing you describe. Some bronze is rather "dry" and does not make a good rotational wear bushing. If you find that the joint stays dry and squeaky, you may have to use oil impregnated bushing material aka Oilite.

 

[Fcvapor05]

Glad to hear you figured out how to cut the shaft.

You should probably also order a new blade for your bandsaw.

 

[firworks]

As a note for future projects, you can order undersized dowel pins. Larry G is correct that standard dowel pins have a + tolerance zone, but undersized dowel pins are +0 / -0.0002 (in 1/4" size). You can also order oversized dowel pins if your hole is a little too large. All three versions are pretty common, you can get them from McMaster Carr.

Those dowel pins look like they would have worked well too. This shaft though has a beautiful fit in the bearing in this case. I'll keep them in mind if I make another one (which I may be).

For those not keeping up, the OP has already made the cut.

Just use an abrasive wheel. It'll cut it easily. Let us know how it turns out!

Also....you could take an old hacksaw blade and braze small pieces of carbide to every other tooth, then.....

I didn't even think of that! Now I just need to get scrap carbide and find my brazing rods and...

Bronze sometimes is not the best for the type of bushing you describe. Some bronze is rather "dry" and does not make a good rotational wear bushing. If you find that the joint stays dry and squeaky, you may have to use oil impregnated bushing material aka Oilite.

I've got a lot of bronze worn off onto the shaft already. The end of the shaft that's in the bearing is totally gold colored. It's still running real smooth but I wonder how long it will last.

Glad to hear you figured out how to cut the shaft.

You should probably also order a new blade for your bandsaw.

Yeah I think that one's probably toasted but the M12 bandsaw blades come in packs of 3 so I've got 2 more.