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Mark C.

Member Since 09 Jan 2012
Offline Last Active Today, 12:15 AM

Posts I've Made

In Topic: Metal Frame For Sprung Arch Kiln

Today, 12:15 AM

My choice would be to build a metal roof over kiln and forget the waterproof layer-I have never seen one hold up and they always crack and leak as the kiln will expand and contract more than you think.

Scrap yard is good start-

In Topic: Not So Obvious Problem

Yesterday, 10:26 PM

Make sure you make this element connection as Dick says back a bit so it runs cooler.Also any loose connections as well as any with corrosion or scale on them will heat up so cleaning them down to bare metal is always good idea and get them as tight as you can.The high amp draws of an electric will kill any dirty or loose connections fast.Clean it all before assembling-

I use  a copper coating as well on most electrical screw  connections that may heat up but its hard to find and costly.It prevents corrosion and handles heat well and is mostly ground copper.

In Topic: Metal Frame For Sprung Arch Kiln

Yesterday, 08:31 PM


DO NOT use springs. The arch will just push them out and they will not return (this is from experience) so do not do this.

The arch will expand up when you have the angle iron in place and the kiln heats up.

Your arch needs to be supported with a form (usually wood) and you can not remove this form until the angle iron is in place-hope thats clear enough.Other wise the arch will fall dawn as its not supported as it spreads out. 

You need to have all 4 corners braced as well-the stem wall as you call it. Its best to wrap the arch on all sides-the front  and rear you can support higher up on the corner frames so the arch is not impeded with iron in the way.

Think of this as a box around the arch with the front and back higher up.

You also need this box at the bottom of kiln. You can in the front anchor to a concrete slab to keep iron from the front under your feet. This is an option- Drill and anchor with concrete bolts into the angle with feet wielded on.

I  to build the frame after the walls are up but it can be done 1st as long as your measurements are firm.

Use thick angle on the 4 uprights as they will take the forces of the arch spread and most under size the metal. as well as along the two sides of the arch as thats where it wants to spread out. I like 1/4 angle on my corners.

My salt kiln uses 1/4 x 3 inch wide angle. I also have a little 1/4 x 2 inch and some 1/4 inch 2 inch  channel which has a 2 inch flat side.

Kilns use a lot of steel. I primed mine and spray it with high heat aluminum paint on all kilns.I have  a friend who is a 1st class wielder -I have the cut off saws and wielder but he brings his own DC wielder for bester control.

Do not add wiggle room to the arch make it tight and that will allow it to expand up not out when its hot.Forget the springs idea-You do not need this.

So to be clear put up the side angles going up (veritcal)1st then build a box to floor level and arch level(horizontal) You will find its best to make the front and rear horizontals be higher than the arch to get out of the way so make the angle sides higher to accommodate this in one long piece on each corner.

I wrap the kiln in the middle along the 3 sides as well with channel.

All thread can be used but make sure its big enough. On the salt kiln we just wielded the whole frame and I'm very happy with that . My car kiln has threaded rods but it never repeat never needed to be adjusted in 3.5 decades.

Plan on spending some $$ on iron.

Hope this was in the budget .

In Topic: Qotw: Do You Have A Question For Us?

Yesterday, 04:05 PM

No I have returned from Cambodia and Indonesia (Wakatobi Indonesia -Swiss owned resort) and am back making pots for gallery spring orders and paying taxes-The month away went quickly.

In Topic: White Lead

22 March 2017 - 02:46 PM


About 10 years ago I found I had a new unopened 50# bag from the 70's of white lead. My guess is I got this bag when buying out a few potters in the 70's and 80's when I got everything they had.

I just waited for a toxic disposal day in our area and took it along with some paints-cost was $5 per car load.

You should deal with this like that as its a hazard to the environment and not be tossed or sold.