Small Heat Treat Oven

[Brian Rupnow]

The frame is completely fitted and tack welded, and the oven and control are in place for test fit. The old red stick welder fits right in where it always sat, but I have it removed right now because I had to get down where it was to put some woodscrews into the framing on that wall. I'm going to move that air hose reel about three inches to the right, and all the stuff that was hanging on that wall is going to hang on a different wall. I'm quite happy with this. I will now put the oven and controller back in the house, take down the frame, and finish welding all the joints.

 

[MJOSPINA]

Nice project, Brian. Maybe the questions is what is the highest temperature you can reach with the oven

 

[HennieL]

The discussion is interesting but I doubt that Brian's kiln is capable of reaching the temperatures needed for heat treating tool steel. I think that his goal is to merely anneal cast iron rings and that is 1100 F.

Well Gordon, O1 is tool steel, and it's only heated to around 800°C - 820°C... The point of mentioning high alloy stainless and high speed tool steels' heats was not that Brian would necessarily need (or want) to harden these steels, but rather to point out that these high temperatures take longer to equalize back to the required temperature once one adds the part to be hardened into the pre-heated oven/kiln, due to the higher target temperature required.

Not that it is very difficult to heat the martensitic stainless steels - I do it all the time using a small electric HT oven (not an industrial oven), and I dare say that Brian's pottery oven can heat just as high. Now heating HSS is a different kettle of fish - the 1150°C (2100°F) really pushes my oven to the limit, but even so, I have very successfully (and more than once...) hardened Bohler S705 (equivalent to AISI M41) to an after temper hardness of 65.5 Rockwell C in my little oven, so it can be done. Here is one of my wood-turning chisels that I made with this steel:

 

[Gordon]

I guess that I just never thought about using my kiln for that. I bought it to anneal cast iron rings and that is all that I have ever used it for. I have made quite a few parts from W-1 but I used the torch to heat them to carrot color, quenched them in water and then tempered them in a toaster oven. I heat rings to 1100 F and W-1 requires 1425 to 1500 F so I am sure that my kiln is capable of that. Looks like I have something new to try. Too soon old and too late smart.

Gordon

 

[ajoeiam]

snip
Here is one of my wood-turning chisels that I made with this steel:

Hmmmmmm - - - - I would be quite curious as to the process you followed to make this.
A description of some kind please?

 

[HennieL]

Hmmmmmm - - - - I would be quite curious as to the process you followed to make this.
A description of some kind please?

I don't think we should hijack Brian's threat any more than we already have (apologies Brian...). I will post a new thread on this - now should it be under "Tools" or under "Metals"... hmm, rather under "Tools", I think...
I will have to just gather my info (I think I took a few photos at the time, but will have to search for them)... Will probably only post this evening (local time)

 

[HennieL]

I will post a new thread on this - now should it be under "Tools" or under "Metals"... hmm, rather under "Tools", I think...

OK ajoeiam, just for you
Heat treating high alloy and high speed steel tools

 

[awake]

Hennie, some very helpful information - I look forward to reading the new thread as well.

 

[willray]

... Now heating HSS is a different kettle of fish - the 1150°C (2100°F) really pushes my oven to the limit, but even so, I have very successfully (and more than once...) hardened Bohler S705 (equivalent to AISI M41) to an after temper hardness of 65.5 Rockwell C in my little oven, so it can be done.

--edit--
(I notice, HennieL has responded to my plea even as I typed!)
--end edit--

Ooh, ohh - someone who will admit to successfully heat-treating HSS, rather than intoning the gospel homile "it's complicated, and can't be done"!

Pray tell - could you give some ballpark starting advice or pointers to guidance that does not require a lifetime's investment in learning the holy language spoken in the industrial HSS inner sanctum?

I ask because I have something well north of $10K of decent-quality HSS cutting tools - primarily Chicago Latrobe, Morse and Cleveland Twist Drill - that I successfully annealed by passaging them through my shop fire. Yes, it got that hot - my shop fire puddled cast-iron tools, and turned barrels of silicon flour into glass plugs. If I can salvage mild-steel, or even just woodworking capability out of even a small fraction of the tooling, I'll be thousands of dollars ahead of buying it all again.

I realize that I don't know most of the alloys, and the random time/temperature soak to which everything was subjected makes any attempt to be precise about moves from their current state into a joke. I can live with that - even a small percentage of successes is better than nothing. 20x my insurance payout won't come close to making me whole, so I'll take anything I can get.

 

[HennieL]

Pray tell - could you give some ballpark starting advice or pointers to guidance that does not require a lifetime's investment in learning the holy language spoken in the industrial HSS inner sanctum?

I ask because I have something well north of $10K of decent-quality HSS cutting tools - primarily Chicago Latrobe, Morse and Cleveland Twist Drill - that I successfully annealed by passaging them through my shop fire. Yes, it got that hot - my shop fire puddled cast-iron tools, and turned barrels of silicon flour into glass plugs. If I can salvage mild-steel, or even just woodworking capability out of even a small fraction of the tooling, I'll be thousands of dollars ahead of buying it all again.

Willray, please see the link in my earlier reply to ajoeiam - I started a new thread on this topis, so as to not further hijack Brian's thread. Won't you just repeat your questions there (just to keep the thread neat...), and I will respond as best I can.

Hennie

 

[willray]

Willray, please see the link in my earlier reply to ajoeiam - I started a new thread on this topis, so as to not further hijack Brian's thread. Won't you just repeat your questions there (just to keep the thread neat...), and I will respond as best I can.

Absolutely - I had started my post to ask last night, but didn't get around to clicking "post" until I got to the office this morning, and then discovered that in the mean time, you'd already granted my half-written wish No desire to hijack Brian's thread!

 

[Brian Rupnow]

The frame that supports the heat treat oven is finished. It is fully welded and even painted. The old Lincoln A.C. welder even got a new handle out of the deal.--It had a handle on it to move it around years ago, but for some reason I had cut the handle off, and I can't remember why. The next stage of this game is going to involve figuring out the control for the oven. It is intimidating because it has to be programed, and I haven't got the faintest idea how to do that. I have two pages of instructions that came with the controller, and I think they are written in ancient Greek or one of the "dead languages".

 

[HennieL]

The next stage of this game is going to involve figuring out the control for the oven. It is intimidating because it has to be programed, and I haven't got the faintest idea how to do that. I have two pages of instructions that came with the controller, and I think they are written in ancient Greek or one of the "dead languages".

Not in official Chinglish?

Brian, as posted earlier, just switch it on, and play around with changing the SV (set value). If this works, you are well on your way to mastering it.
Please send me (or just post here...) the manufacturer's name and/or model number of the PID itself (not the whole controller) - this should be somewhere on the PID - or just post a close-up photo of the unit. If we can identify the make and model number, we should be able to download the instruction manual, and then it should be easy to go on from there.

 

[awake]

I have two pages of instructions that came with the controller, and I think they are written in ancient Greek or one of the "dead languages"

γεγραμμένην ἐν τῇ Ἑλληνικῇ γλώσσῃ τῇ κοινῇ ἐστὶν; αὐτὴv καὶ γράψαι καὶ εἰπεῖν δύναμαι. σοι βοηθῆσαι θέλω.

 

[Gordon]

γεγραμμένην ἐν τῇ Ἑλληνικῇ γλώσσῃ τῇ κοινῇ ἐστὶν; αὐτὴv καὶ γράψαι καὶ εἰπεῖν δύναμαι. σοι βοηθῆσαι θέλω.

That is what my controller says also.

 

[awake]

That is what my controller says also.

Uh-oh, that's not good. It translates to an offer to help ... without actually helping at all!

 

[Gordon]

Uh-oh, that's not good. It translates to an offer to help ... without actually helping at all!

Actually I did manage to understand it enough to get the controller to work along with some trial and error. I was only interested in getting the controller to attain a temperature so cycles and different temperatures were not necessary. I wanted to get to x° F and I have a clock which I could watch to turn it off after the required time period.

 

[awake]

Actually I did manage to understand it enough to get the controller to work along with some trial and error. I was only interested in getting the controller to attain a temperature so cycles and different temperatures were not necessary. I wanted to get to x° F and I have a clock which I could watch to turn it off after the required time period.

Ah, I see a potential problem - the ancient Greeks did not use Fahrenheit, so this may be throwing off your settings ...

 

[HennieL]

 

[Gordon]

The sun dial is not as accurate as I would like to be either.