1095 HT Soak time

J

JimDiGritz

Joined
Oct 18, 2021
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50
So some of you might be following my saga with a new HT oven.

I've encountered another issue.

The oven takes 64 mins to reach 800c. When I open the door (it's an automated hydraulic door) and put the blades inside - by the time it shuts the temperature is down to 530c.

Do I include the 25+ mins it takes to get back up to 800c in the Soak time? Eg do I wait 25mins for it to get to 800c again THEN start my 10 min timer? *EDIT* Bear in mind that it gets back to 770 in 10mins, it's the last 30 degrees that takes another 15+mins...***

I've read that I should soak 1095 @ 800c for at least 10 mins. I've also read that prolonged exposure to high temps can cause grain formation. Does being in the heat during the re-ramp for 30mins affect the steel?

If it doesn't, would just leaving it in the oven from the beginning be very similar??

Thanks

Jim
 
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JimDiGritz said:
Thanks, I was worried that the extra 30 mins ramping back up to 800 would cause an issue, since it's spending a total of 40+ mins in a 700c+ oven.
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I always allow my oven to get up to temp first before putting my blade in. The re-amp hasn’t caused any issues that I’m aware of. Mine isn’t a paragon but it usually takes around 20-30 minutes to reach the set point after placing my blade in as well.
 
TheEdge01 said:
I always allow my oven to get up to temp first before putting my blade in. The re-amp hasn’t caused any issues that I’m aware of. Mine isn’t a paragon but it usually takes around 20-30 minutes to reach the set point after placing my blade in as well.
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Awesome, am glad this isn't a deal breaker!

Given that this isn't a Knifemaking designed oven I'm second guessing everything! A few weeks ago I was happily using my MAP gas forge and checking temperature with a magnet and by colour!!

Now I've got mission control level of data it all seems so much more complicated!!!!

BTW here is the door opening mechanism - I hit the close button at maybe 90% open just to demonstrate the minimum time I can reasonably open, insert/remove blade and close.


You *can* open manually however it's a two handed job and it doesn't stay open - so pretty impractical when HTing. Hopefully the 40sec open time window isn't going to cause me too many headaches.....
 
JimDiGritz said:
The oven takes 64 mins to reach 800c. When I open the door (it's an automated hydraulic door) and put the blades inside - by the time it shuts the temperature is down to 530c.

Do I include the 25+ mins it takes to get back up to 800c in the Soak time? Eg do I wait 25mins for it to get to 800c again THEN start my 10 min timer? *EDIT* Bear in mind that it gets back to 770 in 10mins, it's the last 30 degrees that takes another 15+mins...***

I've read that I should soak 1095 @ 800c for at least 10 mins. I've also read that prolonged exposure to high temps can cause grain formation. Does being in the heat during the re-ramp for 30mins affect the steel?

If it doesn't, would just leaving it in the oven from the beginning be very similar??

Thanks

Jim
Click to expand...
After oven reach 800 c , did you you leave it for at least half an hour on that temperature to soak and after that you open door to insert knife ? Oven build with bricks need longer time to soak before you start to use it .
If your blade is protected from decarburization you have not problem , start time when oven again achieve 800 Celsius .
 
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JimDiGritz said:

You *can* open manually however it's a two handed job and it doesn't stay open - so pretty impractical when HTing. Hopefully the 40sec open time window isn't going to cause me too many headaches.....
Click to expand...
You can change that time ? I can t see on video how the hydraulic piston is connected to the door but if you change position where hydraulic is attached to door mechanism you can speed up or slow down door movement ?
Moving point where hydraulic clip is connected closer to pivot point would speed up movement of door
 
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Natlek said:
After oven reach 800 c , did you you leave it for at least half an hour on that temperature to soak and after that you open door to insert knife ? Oven build with bricks need longer time to soak before you start to use it .
If your blade is protected from decarburization you have not problem , start time when oven achieve 800 Celsius .
Click to expand...
My last test failed because there was a future target temperature still set at Tempering (260c) so the oven started to drop once it reached 798 even though I had asked it to hold this for 40 mins - I guess it was trying to get down to 260 after that 40 min soak time - I thought I had cleared the program out but must have left a target temperature at the end.... frustrating. This is where a standard PID without ramp/soak timers would be much easier....

I won't get a chance to try again until tonight or next week since when the 3.6Kw HT oven is on you can't use any other household appliance (toaster, kitchen oven, iron, washer, coffee maker) without tripping the consumer unit. :oops:

Anyway, to clarify, the suggested order is this:

1. Heat to 800c. 0-64min
2. Leave empty chamber to soak for 30 mins. 64-94min
3. Open and place 1st blade in. Leave to re-ramp to 800c. 94-124min
4. Leave blades to soak @800c for 15mins. 124-139min
5. Remove 1st blade & quench. 140min
6. Repeat Step 3 onwards for each blade.

I hadn't realised that HTing 3 blades would take 3+ hours.... another failure of my research!!!!!!!!!

Jim
 
Natlek said:
You can change that time ? I can t see on video how the hydraulic piston is connected to the door but if you change position where hydraulic is attached to door mechanism you can speed up or slow down door movement ?
Moving point where hydraulic clip is connected closer to pivot point would speed up movement of door
Click to expand...
Hmm, I can't see how I'd move it - I like the thinking but the way it's setup means I don't think repositioning it is realistic without major re-engineering!

No speed control on the door sadly!
 
Wow. Yeah you'll want to get rid of that whole hydraulic rig completely and just open and close the door manually. You will lose some heat of course, but it will rebound in just a few minutes after inserting the knife. Just start the 10 minute soak once your readout has rebounded back to your target temp.
 
That door opening time is painfully slow. The oven also has a lot of volume which is not being used and I would suspect is a significant factor in the re-heat time. I would look into introducing something with significant thermal mass (eg. sand or something similar) which would hold a lot of heat for when the air rushes out from opening the door.
 
You might consider changing the hydraulic piston/cylinder for an air cylinder and a foot switch. Use a pressure regulator to set the speed. You step on the foot switch and the door opens. Let off the switch and the door closes.
 
I agree with the above... a faster door mechanism would help quite a bit. I'd also see about adding an additional layer of insulation around your oven. How hot is your outer oven shell getting?
 
Here is a thought, the door on my Paragon HT14 has the hinge at the bottom. You can google an image real quick to check it out. It's extremely simple. If you could just get rid of the hydraulic thing altogether and hinge the door on the bottom, I don't see why you would need two hands to open and close it. I can open and close the door on that paragon with a pinky finger, as the handle itself has weight to it that keeps the door closed shut. The handle weight is almost balanced with the door weight, but just a little bit more than the door weight. So when you close the door it stays shut. Good luck!
 
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