Help - Cutting Valve seat
- Thread starter chads
- Start date
Help Support Home Model Engine Machinist Forum:
- Joined
- Dec 28, 2008
- Messages
- 1,731
- Reaction score
- 9
Don, there's a good amount of information and discussion on this very subject. start on page 36.
http://www.homemodelenginemachinist.com/index.php?topic=10831.525
-MB
http://www.homemodelenginemachinist.com/index.php?topic=10831.525
-MB
MB,
Great post on valves!!
Im in the process of a build of one of the Upshur Farm engines and have just reached the valve/valve seat part. Ive been following Brians build of the Kerzel and the problems hes had with the valves and then reading your post, Im beginning to wonder if Ive jumped ahead of my skill level. (Way ahead!)
I do have a question . Why all of the effort in making the seat ream when the seat is aluminum and the valve itself is steel? I would think that you could cut a perfect seat and then when using valve grinding compound for the final seating, you would basically destroy the aluminum seat and it would take on any flaws in the steel valve itself. Why not just start with the actual valve and use it to cut the seat?
(Or am I thinking too simply?)
Dean
Great post on valves!!
Im in the process of a build of one of the Upshur Farm engines and have just reached the valve/valve seat part. Ive been following Brians build of the Kerzel and the problems hes had with the valves and then reading your post, Im beginning to wonder if Ive jumped ahead of my skill level. (Way ahead!)
I do have a question . Why all of the effort in making the seat ream when the seat is aluminum and the valve itself is steel? I would think that you could cut a perfect seat and then when using valve grinding compound for the final seating, you would basically destroy the aluminum seat and it would take on any flaws in the steel valve itself. Why not just start with the actual valve and use it to cut the seat?
(Or am I thinking too simply?)
Dean
- Joined
- Dec 28, 2008
- Messages
- 1,731
- Reaction score
- 9
deadin said:
Hi Dean. The only way to progress into a higher skill level, is to take on more than you think you can handle at the present level. (I think I said that correctly). One would think that just grinding the valve seat with the valve stem would work. I did it twice on air engines and it actually did. The compound could embed itself in the softer aluminum head, and end up grinding the valve Some experienced builders cut a small seat first with a simple guided cutter. This assures the seat is cut concentric with the drilled and reamed hole in the valve guide or valve cage. The reason for using a cutter is that a drilled and reamed hole is likely to go a bit off 'dead center' to cause a seating problem with the valve. I'm getting close to making the valves for my Upshur builds, and will soon be facing the same issues and concerns. You could work on some other parts and hold off a bit on your valves, just to see how I end up handling the 10 valve's I need.
-MB
If you trust the concentricity of the headstock to the tailstock on your lathe 100%, then you may very well get away with machining the valve guide and the valve seat all in one set-up and you will be finished. But "May very well" is not a complete assurance. I have one I.C. engine under my belt that runs very well, and the valves were machined exactly as stated above. I am now in the final stages of a hit and miss I.C. that I built this fall, and have had a world of problems with my valves not sealing properly. I went so far as to make a "valve seat cutting tool", and I'm still having major issues. The only difference is that the lathe and I are both a year older.---I don't think thats hurt me too much, but there are a lot more hours on the lathe than there were a year ago. I am at the point now of machining new valve cages and testing them externaly before installing them, as described in the post you were referred to. It seems to be "The luck of the draw" as much as anything.---Brian
Don---I'll say you probably can do it that way, but you will never be sure until after the fact. Just keep the seat very very small, as in .005 to .015 deep.
- Joined
- Dec 28, 2008
- Messages
- 1,731
- Reaction score
- 9
chads said:
Don, if 'your not sure' if your idea will work, then why waste your time taking a chance? If the valves don't seat properly do you have extra heads? Do you see where I'm going with this post. I don't mean to sound rude, I'm just stating cold-hard-facts. I usually do all my machining in one set-up and get good results, but valves seating needs to be damn near perfect, or no cigar!
I just came up from the shop after cutting 22 valve stem heads (lots of extras, just in case), And with the lathe set up to cut the proper angle, my next step is to start on the 'valve seat cutter'. I've mentally wrestled this subject for a long time, and now I know what needs to be done for my own peace of mind.
Many have had success doing it the way you per-pose, and If you go that route, I sincerely wish you the best of luck.
-MB
chads
Well-Known Member
- Joined
- May 27, 2010
- Messages
- 79
- Reaction score
- 4
I havent reached the point yet where I am working on the head but pretty close. I am always thinking one step ahead. I like the idea of making a seat cutting tool but also thought the countersink might be an option. Being that I only have one head, I need to choose the best option. Apparently there is no magic answer to this question ???
Chads----I just finished building my second I.C. engine, the Kerzel hit and miss. It is all built from bar stock, no castings, and it called for machining the valve seats directly into the cylinder head in the same set-up as drilling the valve guides. Either due to my lack of machining experience, bad karma, or some how I p**sed off the machining gods, I messed it up and my valves wouldn't seal. I went through many stages, drilling the head out for valve cages, making new valves, making a second set of valve cages, and making a valve seat cutting tool. Eventually, I was succesfull, and got my valves to seal, but I don't think everybody should start by building the valve seat cutting tool. It simply may not be necessary. Hundreds if not thousands of small I.C. engines have been built by amateur machinists without having to build this tool. I built it as a last resort, and it did solve all my problems, but I would try it without the tool first. Metal Butcher is a very talented man, and he is building multiple IC engines at once, so yes, for him its probably a great idea.----and Oh Yeah---If you do decide to build the tool, its not difficult at all. I built mine (its covered in the last 5 pages of my Kerzel thread) and it was surprisingly easy to build and to use.
- Joined
- Dec 28, 2008
- Messages
- 1,731
- Reaction score
- 9
chads said:
Chad, its an option, but not a good one. There is a good chance that the drill will go off center, and the reamer will defiantly follow. I have seen this happen many times. In a lot of cases the small discrepancy will go unnoticed with no ill effect. A valve stem seat is another story, and not a good place to try a short cut method.
There is a magic answer. Cut your valve seat guided by the reamed hole that will guide your valve. :idea:
-MB
Okay---MetalButcher wins!!! Here are a couple of pictures of the tool I made. Its made out of water hardenning drill rod which is miserable damn stuff to get a good finish on---although nasty looking, that .094 end bit was exactly on size, and I didn't want to take anymore material off to smooth it out or it would have been undersized. As I said, not difficult at all to make, and it works like a charm---I was using mine on brass valve cages, so I simply turned it by hand to cut the seats. the big trick with these small seats is to keep them very small---almost a line contact, as it were with the valve.
Brian, I see your valve tool, looks good. Didi you harden it? I cut most of my valve seats
in CI, and was wondering if it would be best to harden the tool.
I have made one of these in the past when I built the Marion. The valves are way down in the
cages, and I had to have a tool like this. It dulled badly after 2 valves, fortunately that's all I needed and the engine runs very nicely. I didn't harden the tool, but I don't remember if I
cut the scale away first. These cages were cored and there was likely some hard crust internally that was not removed by the bead blasting.
maury
in CI, and was wondering if it would be best to harden the tool.
I have made one of these in the past when I built the Marion. The valves are way down in the
cages, and I had to have a tool like this. It dulled badly after 2 valves, fortunately that's all I needed and the engine runs very nicely. I didn't harden the tool, but I don't remember if I
cut the scale away first. These cages were cored and there was likely some hard crust internally that was not removed by the bead blasting.
maury
I did harden it by heating to a cherry red, then dunk straight down into a container of water and swirled around. Its harder than the devils horn!!! I didn't "draw it back" afterwards to temper it----its just like glass its so hard, but for what I needed thats okay. If it was going to be ran in a power tool, it should be tempered, but the whole issue of hardening steel is breaking new ground for me, and I didn't want to mess it up.
brian did you chuck up your cutter after heat treating it to make sure that the small end did not move , after dunking it in the cold water. i have done alot of heat treating of oil hardening tool steel and some water hardening and usually something that small does not stay to straight. if it does not you could chuck it up in a collet and check wiht an indicator and bump it with a piece of brass to get it running true. just wondering. jonesie
No---Well actually I just chucked it up and spun the lathe. Its out a bit, but not enough to impair its function. Thats one of the reasons for dipping it straight down into the water---If it goes in on an angle or sideways, the uneven cooling will pull it off center. And as I said, its harder than the devils horn and brittle as glass---I'm not about to attempt straightening it. the engines running fine now, so I'm not interested in making work for myself that I don't need to..
Similar threads
