Using DOM or seamless stock as a starting point for cylinders

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WhiskeyHammer

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I'd like to save myself some work and use an existing pipe or tube for the cylinder in my ICE build. It's a wide world of pipe and tubing out there and it looks like both the material and the method of manufacture matter a great deal. So the general theme of my question is this: What style of pipe or tubing would be feasible for use as a cylinder?

I understand that some level of processing is unavoidable. I'm sure I'll need to ream and hone to get the geometry on the ID right, but it seems like it would be both less costly and easier to start with a piece of stock that's already pretty close.

From my research into the materials side of things, it looks like aluminum and cast iron are the go too materials but even then there are different types. These are the types that I see referenced most frequently.
Cast Iron: Grey or ductile, I'm not sure which grades are considered best​
Aluminum: 319, A356, A357, 6061​

From the manufacturing side, I think DOM or seamless is the way to go. I'm not sure that I would trust welded.

So to give a ballpark answer to my own question. In theory any pipe made of grey or ductile iron, or any of those four aluminum alloys, and made with a DOM or seamless process should work.

To resolve my general question into specific functional ones:
  • Are there any grades of grey or ductile iron that are especially good or bad?
  • Do you forsee any problems with starting from DOM or seamless?
  • Is the idea of using an existing pipe offering sound or am I missing something?
 
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dnalot

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I used DOM steel when I built my Holt. Worked fine for me. The DOM steel formed the water jacket and I used cast iron for the sleeved liner. I think it would work OK as a cylinder without the liner..

Mark T
 

BaronJ

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Hi Guys,

A useful source of seamless steel tube is car shocker absorbers or dampers !

Carefully drill a small hole in one end and drain the hydraulic oil out. Then cut up as required.
 

mayhugh1

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I've wondered about using DOM tubing as well. It would save the tedious i.d. roughing step. There have been many model engines made using aluminum pistons with cast iron rings in steel cylinders including the Hodgson radials. Nearly all the engines I've built have steel cylinders or steel liners with cast iron rings. The i.d. of the DOM tubing might be surprisingly accurate with only lapping required if you're willing adapt the design of the rest of the engine parts to use it as is. If you're planning to make your own rings, the rest should be easy. - Terry
 

dsage

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DOM worked fine as-is for my Parcell and Weed full sized engine. 2-1/4 bore. I just honed it to get a cross hatch and that was it. BUT be very careful it is true DOM tubing. The supplier I use pointed me to a part of their shop where the DOM was supposed to be and there was a lot of tubing on the rack that had a slight seam. The true DOM is perfectly clean inside. You can't remove the seam by any amount of boring / honing etc. I made that mistake on another build.
I made the piston and rings to suit the ID of the tube. (Aluminum piston and cast iron rings)

 

ajoeiam

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I's like to save myself some work and use an existing pipe or tube for the cylinder in my ICE build. It's a wide world of pipe and tubing out there and it looks like both the material and the method of manufacture matter a great deal. So the general theme of my question is this: What style of pipe or tubing would be feasible for use as a cylinder?

I understand that some level of processing is unavoidable. I'm sure I'll need to ream and hone to get the geometry on the ID right, but it seems like it would be both less costly and easier to start with a piece of stock that's already pretty close.

From my research into the materials side of things, it looks like aluminum and cast iron are the go too materials but even then there are different types. These are the types that I see referenced most frequently.
Cast Iron: Grey or ductile, I'm not sure which grades are considered best​
Aluminum: 319, A356, A357, 6061​

From the manufacturing side, I think DOM or seamless is the way to go. I'm not sure that I would trust welded.

So to give a ballpark answer to my own question. In theory any pipe made of grey or ductile iron, or any of those four aluminum alloys, and made with a DOM or seamless process should work.

To resolve my general question into specific functional ones:
  • Are there any grades of grey or ductile iron that are especially good or bad?
  • Do you forsee any problems with starting from DOM or seamless?
  • Is the idea of using an existing pipe offering sound or am I missing something?
Out in the world hydraulic cylinders are most often made from DOM tubing using cast iron for the piston head.

Air cylinders (not very conversant here - - - just a wee bit) seem to often be aluminum and dunno about the heads.

AIUI the cylinder and the heads should be dissimilar materials - - - that minimizes any potential galling.

DOM tubing is used as the elastomeric sealing ring and maybe more so the wipers are used to keep the piston from contacting the cylinder walls.
Variations of a thou or two are terefore considered unimportant - - - - in hydraulics.

(If you're using DOM tubing for steam cylinders - - - that's a different world and then the above does not apply.)
 

oldengineguy

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I have used DOM tubing and turned the od and id to suit the 1 in. bore and press in od of finned aluminum sleeve of a copy of a Panther pup. Took a while for the rings to bed in but after reading the great debate about rings recently perhaps this was due to 062 wide purchased rings rather than unsuitable material for the cylinder. The bores were honed on a friends Sunnen piston pin hone so they were straight and round. I will likely use DOM again as it's cheaper than cast iron. Colin
 

trackmaggot

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DOM tubing is fabricated from flat strip stock, so it will always have a seam. When done properly, the seam is next to invisible because of the cold work done as the tube is drawn over the finishing mandrel. The process delivers very consistent OD, ID, and wall thickness, while delivering good surface finishes, and the weld itself undergoes significant improvement in mechanical properties

To get truly seamless you have to find either extruded, or pierced billet (A.K.A Cold Drawn Seamless).
 

lkrestorer

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A useful source of seamless steel tube is car shocker absorbers or dampers !

Carefully drill a small hole in one end and drain the hydraulic oil out. Then cut up as required.
This sounds like an interesting idea. What diameters and lengths are we talking about with normal shock absorbers?
 

lkrestorer

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And ........ what about used or discarded hydraulic cylinders? Is this a possible source of liners where a project's measurements might be adjusted slightly?
 

trackmaggot

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Hydraulic cylinders are usually DOM or CDS, and have very fine internal surface finishes. Used you would have to check for scoring or other damage; other than that they are fabbed for high pressure, to fairly tight tolerances. As long as the wall thickness is in the range needed, should be GTG.
 

Ed T

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One thing to consider when using tubing (as opposed to pipe or other things with a hole in the middle) is that the OD is very closely controlled to maintain compatibility with tubing fittings. The wall thickness is fairly well controlled consistent with the pressure rating of the tube. The ID is whatever is left over and is not as well controlled as the other parameters. So, to use it for a cylinder you will be faced with machining the ID to make it round and some particular diameter. This operation can be difficult because holding on to the tube w/o making it un-round is tricky. As mentioned above hydraulic and air cylinders, generally, use elastomeric or other compliant seals so smooth is important, but size and roundness are quite forgiving.
 

Ed T

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DRAWN OVER MANDREL TUBING
Drawn Over Mandrel Mechanical Tubing (DOM) is a cold drawn 1020/1026 electric resistance welded tube with all of the flash removed prior to cold drawing. In comparison to traditional electric welded tubing, DOM tubing is produced to extremely tight OD and ID tolerances. This type of tubing is also known to have the highest weld strength possible. DOM is manufactured in numerous sizes ranging from a 0.188” OD to 12.000” OD with wall thicknesses from 0.028” to 0.625”.

DRAWN OVER MANDREL TUBING MANUFACTURING PROCESS
DOM starts as a large coil of steel which is then cut into strips at a certain width depending on the desired tube size. This strip is cold formed and passed through an electric resistance welder which joins the edges of the strip together creating a tubular shape. The tube is then cleaned and annealed and then drawn through one or more dies and over the mandrel. Drawing the tube over the mandrel removes the weld seam from the inside diameter creating a smooth and clean finish
 

Chiptosser

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Well, it sounds like 4130 chrome moly is the way to go for truly seamless DOM tubing.
 

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