Forges 101

[Mikey98118]

40 minutes ago, timgunn1962 said:

etting rid of an internal coating after the forge is built is a whole different ballgame.

yes; while the inside and outside surfaces of your forge shell are only a few thousandths of an inch apart, the outside is cooled by shop air; a break the inside surface isn't getting.

[Retiry]

I used to sell schedule 40/80 pipe but it has been a long time ago.  I believe the outside is coated with ziebart nothing on the inside. I guess I'm going to fire it with the coating and see what happens. But, first I have to see if it's toxic and I believe ziebart is. I'll have to research it and start with the steel company I worked at many years ago..

 

 

[Mikey98118]

On 11/25/2017 at 9:45 PM, Retiry said:

I believe the outside is coated with ziebart

That sounds like a manufacturer or industry group designation for a particular coating, I can tell you that I have run many of these pipes in burners without any problem. I believe you could run zinc coated gas tubes in burners with little or no problem for the same reason; this part of the burner grows cold while it's run; not hot.

[Retiry]

I want to use 10" sch 40 for a forge. Not burners, ziebart is under coating very popular in the 50, 60, 70s. They used it in the 80s on sch 40 and 80 pipe I was wondering if I should remove it before making a force out of it.

[Frosty]

Pipe, especially threaded pipe always has residue on the inside, water soluble cutting oil from threading, trimming, deburring etc. 

I get some colorful flames like yours when I first fire a burner if the tube gets hot. This doesn't happen with the NARBs there's a wide remove between the tube manufacture residues and the fire. 

I just let it burn out while I'm doing something in fresh air. You can hear if something goes wrong and be back to the shut off in a flash. Were I doing it other than in my concrete and steel "nothing flammable in it that would bum me out if it burned" shop I'd do the breaking in and tuning outdoors.

Frosty The Lucky.

[Retiry]

Sounds like a good idea to light it up outside. Speaking of Frosty. I'm making T burners.

I'm using schedule 80 for the pipe into the T. It calls for 1/8 pipe. I drilled the 5/16 tapped it with 1/8 npt.  The tapped hole is too small for the sch 80 pipe. Yet I retapped with 1/8 npt mpt. And it fits into the hole in the T. Yet like Frosty says in the plans the hole in the schedule 80 is almost the correct size before machined. I'm confused.

[Jasent]

1 hour ago, Retiry said:

Frosty says in the plans the hole in the schedule 80 is almost the correct size before machined. I'm confused.

I believe he was talking about tapping for the mig tip.  1/4x 28tpi or 1/4 x20tpi dependant on which mig tip brand your using

[Retiry]

Look in the part labeled alternative. Yes but you have to drill and tap for the 1/8 sch 80 pipe that the MIG tip screws into then screws into the T.  I have a 1/8 npt tap and it is much smaller than the 1/8 pipe pipe..

 

[Jasent]

Somethings off. My 1/8 npt tap worked with schedule 40 and 80. There should be no difference between the two on OD measurement. Only id. Maybe I'm not understanding you.  Prob should continue this discussion in the T burner thread. 

[Retiry]

Your right something is off.

[Retiry]

Those threads are touchy. One tiny Burr and they won't start. So I got them threaded. My fault, I didn't clean them up before trying thread the pipe in. I feel like a jerk. I'm not getting a cone on some of them.

[Jasent]

Glad you got it figured out.  Have you tried them in the forge yet?

[Retiry]

I lit them up and one surges like it's in the wind and the other three don't get a cone just a flame that pops out easily.

[Frosty]

How about a couple pics? Videos aren't necessary stills work just fine. Till we get a look see, how close are the air intakes to the forge's exhaust plume? If the burners aren't burning evenly the exhaust if puffing out in billows which gets sucked in in billows making the burners puff. It's a self amplifying cycle till it blows itself out. That's just a guess without ore info.

Frosty The Lucky.

[Retiry]

I haven't put them in the forge yet. I had them clamped to my bench but, I'll take some pictures tomorrow.

[Jasent]

They will likely act very different Inside the forge. As frosty said pic's would help a lot. 

[Canlib]

Liner and IR coating

I have my 20 pound propane tank prepared, my T burner built and the ceramic blanket and digitizer are on the way from Front Porch Forge in Edmonton, AB.  I'm going to make the liner using 95% Zircopax and 5% Vee Gum T and use the same ingredients to cast the NARB. Can I use Alumina Oxide and Vee Gum for a brush on IR coating or should I stick with a thinner mix of zircopax or order Plistex from Wayne Coe? I can get these ingredients in 1/4 pound or 1 pound bags from Greenbarn Potters Supply in Surry, BC and I'm wondering how much to order for a forge this size.

[timgunn1962]

Has anyone reported any success with the Zircopax/VeeGum as an applied lining yet? If so, I think I've missed it.

I do seem to recall someone (Maarten?) having some success with stand-alone tiles and thin surface coatings. I got the impression that they knew their way around ceramics a bit and had knowledge that those of us with no ceramics experience would need to acquire, probably the hard way. Making stand-alone sections would seem to eliminate many of the shrinkage issues that occur when different materials are used together.

Shrinkage rates with the clay/Zircopax mixtures I've tried have been pretty severe. Once they get to about 1/8"/3mm thickness over rigidized kaowool, the shrinkage means they crack up quite badly on firing. Drying times are also tediously long. I've been using porcelain clay and Zircopax, not Veegum/Zircopax, so YMMV. The porcelain clay is primarily Kaolin/Alumina with added plasticisers, some of which are likely to be Bentonites. Bentonites really do not like letting go of water.

I'm not saying it won't work. There may well be further mileage in the Zircopax/Veegum as a liner, if you are of an experimental persuasion. Unless there's a "this is how I did it and it worked really well for me" somewhere that you can follow, it WILL be experimental. If your main objective is to get on with forging stuff, a digression into forge development may not be for you.

A thin (brushable) Zircopax/Veegum mix should be fine as a surface coating. I've had no problem with thin coatings of the Zircopax/China clay.

I really don't see the shrinkage of Zircopax/Veegum being compatible with the huge cast block that is a ribbon burner though. Far better to use a commercial castable refractory formulated by experts to give minimal/zero shrinkage on (water-) setting and minimal thermal expansion (as this, coupled with temperature gradient, is primarily what causes cracking). Setting time for the castable will be hours and drying time will likely be realistic in many climates (cast it one weekend and run it the next). In cooler/wetter climates, it may need moving indoors to dry once the block is set and the messy bit is over.

 

 

 

[MonkeyForge]

I have had similar issues with shrinkage but mostly on drying. a 4 to 5 mm coating on the arched ceiling of the forge cracked severely during drying. The cracks did not widen on firing so this indicates most of the shrinking occurs during drying. Using less water may be beneficial. On the flat floor the cracking did not occur. I used Bentone, a refined bentonite clay, not Veegum but they are supposedly similar. Drying times are indeed long about a week in a dry shop for the 5 mm coat and it is likely that after this time there is still some water content. Thinner coats and/or a lower water content in the mixture are probably a good way to go. Another thing to note is that the mix is really sticky which is a plus for adhesive properties bubt makes troweling a bit tricky.  I may in the future experiment with adding rigidzer as a glassy binder this worked for me in a mix with Zirconium silicate and kaolin.  Besides the cracks in my last experiment the coating is still pretty tough after firing, especially on the un-cracked floor part. I'll patch the cracks with an adjusted mixture sometime in the future and keep you guys posted. Also on the list is to dewater after mixing and use as a clay rather than plaster, I am curious as to how well the mix will stick to wool in this consistency.

Picture below is after drying and before firing. After firing it looked pretty much the same.

Cheers,

Maarten 

 

[Jasent]

I'm playing with the same mix as monkeyforge. I have learned if the clay has not dried completely before firing then it shatters in to egg shell like peaces. I would recommend baking in an oven first to drive out water slowly like at warm setting 175f ish.  I will continue to test with it as I would like to use as a refactory aswell

[Canlib]

Thank you all for these clear replies!  You saved me from myself!  I'll continue my search for a local supply of high temperature castable refractory.  2200 degree is easy...higher temp not so common.

[Jasent]

@Canlib where are you located? Please edit your profile to show a location. Many answers will be location dependant. 

[Remmie]

On 11/26/2017 at 12:45 AM, Retiry said:

I used to sell schedule 40/80 pipe but it has been a long time ago.  I believe the outside is coated with ziebart nothing on the inside. I guess I'm going to fire it with the coating and see what happens. But, first I have to see if it's toxic and I believe ziebart is. I'll have to research it and start with the steel company I worked at many years ago..

Ziebart is actually a mix of liquid alox sprayed on as a rust proofing. I use it often for a lube additive for cast lead bullets. I have actually thrown old bullets coated with it back in the casting pot where the hydrocarbons actually act like a flux. I wouldn't stand over the pot inhaling it, but overall not to noxious smelling when hot.

[ThomasPowers]

Of course CO is not noxious smelling either.

[Remmie]

Agreed. When I cast lead I always make sure I have very good ventilation, even though bullet casting temps are far below where lead becomes a vapor, I just hate a flux that stinks. Also the MSDS sheets on straight Alox don't show it as being toxic  under x number of PPM. I think you would need to close all doors and windows to reach  that, and anyone running a forge is SUPPOSED to be aware of CO and insure adequate ventilation. I would need to dig out the MSDS sheets to give exact numbers. Basically all I was saying was that the coating may smoke a little and smell, but should otherwise be harmless in a shop ventilated well enough to vent CO.