Werowance builds a webster

[werowance]

well after 3 attempts at making a valve - all ended in failure. the tool post grinder did the best but it still failed. the shaft of the grinder is just to wobbly and not accurate at all. also is under powered so that's a bust as well. I tried with a piece of stock long enough to use a live center and support the tail stock. that failed to. although it was the 2nd best go at it. worst was unsupported and trying to get rid of deflection with files and emory cloth. now all that said I started looking for a better toolpost grinder - something I have wanted for a while now anyway. I found this:

I contacted the person who makes them and he says he still makes them, but hes on vacation this week so when he gets back he will give me a proper quote and such and hopefully this will do a better job if I buy it. was wondering if anyone has used this model of grinder? looks a lot beefier than my little pencil grinder does. and the price on the old ebay listing was right to. but that was about a year old ebay listing. hopefully the price will still be the same...

 

[werowance]

and am also considering a different material than stainless steel for the valve. any thoughts on that?

 

[Cogsy]

I use drill rod/silver steel for IC valves. Cuts easy and leaves a good finish. I cut the valve stem to +0.01mm in roughly 10mm steps until I have the length I need then polish the stem with a bit of emery to size in under a minute. I make a seat cutter for each set of valves I make from one of the valve blanks, so I know the seat angle perfectly matches the valves (I don't have a 1 degree difference between seat and valve). The finish on the valves is good enough that lapping in by hand (into brass valve cages) takes only a minute or two per valve, and I only use standard toothpaste as an abrasive. This works for me and I always get a good enough seal to start the engine.

 

[minh-thanh]

werowance !
More information, with body valve and valve guide, making fit is best, but bit larger tolerances don't matter. The important is the valve surface must be closed to the valve seat surface
This is an my old engine, I often use it to test: carburetor, piston material ..... It always runs with me

 

[werowance]

thanks guys, yeah I was considering silver steel. good to know that's ok to use. did you all have any opinion on that tool post grinder I am considering purchasing?

 

[Brian Rupnow]

I have always used plain cold rolled steel for my valves, and have never had an issue. Before considering any kind of grinder for your lathe, make sure it can be mounted at various angles. The valve stem doesn't need to have a ground finish. Just plain, sharp HSS tooling and a bit of 220 grit sanding strip is all that the valve stem requires. The only part of the valve that would benefit from grinding would be the angled portion of the face that contacts the seat. If your grinder can't be positioned to do that, you are wasting your money.

 

[Mechanicboy]

I never used the tool post grinder on lathe..
It's not difficult to make smooth and true valve stem. Use wet and dry sand paper #200 to adjust the valve stem to be true in length and diameter (check with micrometer between work) and #600-800 for finish surface.

In my engine, the valve is made of stainless steel.

 

[werowance]

i had success using regular steel. or really not sure what steel it is, just that it cuts great and is the slide rods out of the scan bed of a large copy machine from work. I have a few more left and they cut almost like 12l14, have a nickel tint to the steel like stainless and doesn't deflect or spring very much. a magnet will stick to it. using the file and emory cloth method I am used to for unsupported stock to get any defelction out. like others above have described. ill get the 2nd valve cut and then ill make the britenellie seat cutter before moving my compound. I left some handle material on the end so I can lap it easily into the seat then ill part that off.

 

[Mechanicboy]

Look better.. when running the engine, lubricate the valve stem before use. It keep tight with oil when the fuel/air is sucking into the cylinder under start up.

 

[werowance]

yep it does look better than the stainless steel ones I did. all of those failed. happen to have a pic of one of the failures

 

[werowance]

and as you can see by the grain of even the larger portion of both valves the stainless just does not cut very good for me. but I'm off that boat now and on the good cutting steel boat

 

[Mechanicboy]

Don't use the cemented carbide tools for the small and detailed works due not sharp enough. Use HSS tool when turning in the thin material and keep high revolution + very light cut and low feed. Keep HSS sharp with some stroke with diamond hand grinder some time between work. To create smooth surface --> rounded nosed tool. Also not fault with the material, fault selected tool only.

 

[Ghosty]

These are valves I machine out of 316SS, They have a 3/8" dia head and a 1/8" stem, use stainless steel T/C cutters and have no problem. I was given a box of 1000 316SS 7/16x2" bolts with damaged threads(not formed correctly) good for making small parts.
Cheers
Andrew

 

[werowance]

Don't use the cemented carbide tools for the small and detailed works due not sharp enough. Use HSS tool when turning in the thin material and keep high revolution + very light cut and low feed. Keep HSS sharp with some stroke with diamond hand grinder some time between work. To create smooth surface --> rounded nosed tool. Also not fault with the material, fault selected tool only.

rounded nosed tool. I can grind different cutters in hss the standard square tip is the most common shape I use sort of has and angle in all directions - the one in most teaching books as your first hss tool grind. it cuts at a sharp point. but on the round nosed tool. that description could be interpreted differently. so by chance do you have a picture of the tip you are talking about? also the soft steel is leaving a very nice smoothe finish with my insert cutting tool so I am good with that for what I am doing right now but would like to learn and try what you are talking about on as well.

 

[werowance]

this is the square tip I was talking about, found a pic on the net of it

 

[Mechanicboy]

See at the table for lathe tool in angles. There is recommended angles for stainless steel.
https://smithy.com/machining-reference/lathe-turning/page/1

I'm using the left hand finishing with small rounded nose.

 

[werowance]

almost finished up on the valves this weekend. one is cut to length - no photo. made the valve seat cutting tool and it worked well. ground them in with 800 grit laping compound. all seems to fit really well.

 

[werowance]

id like to talk springs this morning please. so for my question, all springs are made of the same gauge wire from the same spool but here are my variables / questions.
1. is a spring with fewer turns per inch stronger or weaker? I think weaker however I wonder if the pitch or angle of a fewer turns per inch spring might actually make it stronger?
2. if a spring is wound smaller (smaller mandrell that its wrapped around) is it stronger or weaker. example both springs 1 inch long, both 15 turns per inch but the 2 mandrells the were made on are 1/2 and 1/4 inch wouldn't the 1/4 inch be considered softer or weaker than the 1/2 inch our would it be the same?

reason I ask is I am considering cutting and then streaching out a spring for the intake to make it much weaker than the exhaust I also have a slightly smaller diameter spring that will fit as well. but the wire guage is the the same.

 

[CFLBob]

I can't answer that, but I sure hope someone else does.

The only theory I know about springs is Hooke's law and spring constants. That ignores the things in your question.

 

[Mechanicboy]

Read this about spring etc.. http://educypedia.karadimov.info/library/springs.pdf