Yet Another Webster Begins

[CFLBob]

oh, and sorry for posting so much but one more thing, Brian gave me some direction on a jig to hold the crank pin in place to drill the hole in the flywheel for timing. it worked great. its in my build but i think it was an awesome trick he gave me.

I'll go look at the build thread.

I went to start on the valves. Changed the cutter on the lathe and lined it up a bit differently. When I went to turn on my lathe, it wouldn't turn on. This is my Sherline, which is about 1/10HP, a DC motor with a speed controller. Since it didn't start running poorly, it just died, I figured it was the controller and not brushes. Took about a day to find out it was just the on/off switch. I had a switch in my pile of junk parts and got it running with only about a two day interruption.

I had figured I'd make a test valve first before I went any farther, working on Brian's approach.

I should have time to get back to this today.

 

[BaronJ]

I spent entirely too long deciding what to build for my first IC engine and finally decided to go with the Webster while waiting for George Britnell to finish his plans for the Holt 75.

Last weekend (11th/12th) was spent tracking down and ordering materials and I had it all by Friday. I didn't get everything, but enough to do a really good start on the engine. In particular, the parts labelled brass and bronze seemed hard to get small pieces of. I need to find a good source for that.

Found and ordered the two gears. My usual source for metals has mostly been Online Metals, but I kept coming up with sizes and costs way beyond what I hoped to pay. With eBay and a seller called USA Metal Online, I was able to save quite a bit over Online Metals for the 3/8 and 5/16" aluminum plates. I bought several smaller pieces from Hobby Metal Kits, but probably saved the most looking for a flywheel blank. The drawing says "CRS or Cast Iron", and the best I was doing was around $33 before shipping for a piece about 2" long and comfortably over 3.75" diameter of 1018 CRS. This was both Online Metals and some eBay searches. Then I ran into a different seller on eBay who had a chunk of what he called D2 tool steel at $18.75 including shipping. I figured the important part was the specific gravity of steel vs. aluminum and bought the D2 blank.

Everything I bought is in and I'm going through the drawings to figure out how to do things, but there's one thing I did that's new to me. The vinegar and salt solution for de-rusting steel really worked.

Of the things I bought, the only thing that was rusty was the flywheel blank and it was totally rusted on the front, back and sides. Since it's going onto the lathe to get cut, that didn't really matter, but I wanted to try that trick. So into a plastic container, covered with white vinegar, and some salt because I didn't know exactly how much vinegar was in the container. After 24 hours it looks like steel. All the surface rust came off. This thing was completely rust colored, without a single spot that was this color. There was really no scrubbing to get to this point. The rust just lifted off.

View attachment 109340

My process is different than most of yours. My mills are both CNC, so I either have to draw the parts up in 3D CAD so that I can create tool paths, or I have to get coordinates of every point on the drawings so I can enter points for holes, or start and stop points on straight cuts. I won't be going very fast.

I use citric acid (Lemon Juice) for de-rusting, its not as vigorous as some. If you forget to take it out, it doesn't mater since it doesn't affect the parent metal like some.

 

[CFLBob]

Does lemon juice take longer than overnight?

I guess most of the time being in there two days instead of one isn't a big deal for me.

 

[werowance]

muratic brick acid from the hardware store on a qtip works well for removing surface rust

 

[CFLBob]

Well, this ain't happening. This is as close as I can get a cutter to the valve to cut the 92 degree included angle on the back of the valve.

This is the test valve on my Sherline micro lathe using their part number 1270 compound slide. I thought this would be a good task for the Sherline because a 1" long part with stem that's .093 is a small part and the Sherlines are good at small. The problem is that the compound slide just won't let me cut that 46 degrees on the end of that shaft. I can't get the cutter within an inch of the part.

Maybe if it was much longer blank that I started with, but I thought being 50 or 60% longer than needed was all I needed. Besides, when I started this, I only had a bit over 3" of 1/4" drill rod available, so I cut it in half. I since bought a 3 foot long piece of rod so I can make the blanks as long as I need to.

Brian, I'm using the method you posted back a few years ago for the valves for another engine that were bigger than the Webster valves. This compound slide won't position the cutter as in your method. It looks like I start over with a longer piece on my 8-1/2 x 20 lathe.

 

[BaronJ]

Does lemon juice take longer than overnight?

I guess most of the time being in there two days instead of one isn't a big deal for me.

Hi Bob,

Citric acid is much more gentle !

 

[BaronJ]

Well, this ain't happening. This is as close as I can get a cutter to the valve to cut the 92 degree included angle on the back of the valve.

View attachment 118110

This is the test valve on my Sherline micro lathe using their part number 1270 compound slide. I thought this would be a good task for the Sherline because a 1" long part with stem that's .093 is a small part and the Sherlines are good at small. The problem is that the compound slide just won't let me cut that 46 degrees on the end of that shaft. I can't get the cutter within an inch of the part.

Maybe if it was much longer blank that I started with, but I thought being 50 or 60% longer than needed was all I needed. Besides, when I started this, I only had a bit over 3" of 1/4" drill rod available, so I cut it in half. I since bought a 3 foot long piece of rod so I can make the blanks as long as I need to.

Brian, I'm using the method you posted back a few years ago for the valves for another engine that were bigger than the Webster valves. This compound slide won't position the cutter as in your method. It looks like I start over with a longer piece on my 8-1/2 x 20 lathe.

Ah the price you pay !
Now if you used HSS and not carbide inserts, you would know how to grind a lathe tool to do this job !

 

[Sprocket]

Ah the price you pay !
Now if you used HSS and not carbide inserts, you would know how to grind a lathe tool to do this job !

You could try making the head first at the right end of the part, leave enough to face off later, use a center to support the end if needed.
Doug

 

[CFLBob]

Now if you used HSS and not carbide inserts, you would know how to grind a lathe tool to do this job !

I think it's easier than that. I think all I need to is rotate the cutter I used to get to that first picture (post 261). A 60 degree triangle for cutting threads would be an even easier cutter.

 

[stevehuckss396]

Flip the cutter to the other side of the tool holder and reverse the angle so the cutter is behind the work and run the lathe in reverse. Then cut from the back side.

 

[stevehuckss396]

You are not cutting the end of the stem, never mind.

 

[CFLBob]

I went with the 60 degree cutter used for threading. The compound slide is useful because of its accurate scale, and a quick check in CAD confirmed I thought of the angles correctly - the cutter should be 14 degrees off from straight into the part.

Yes, I did move the valve a little to the right in the chuck.

 

[Bill Lawson]

I made 4 or 5 valves and failed. I finally decided that .094 thou diameter was too long without deflecting and bending. My solution was to center drill the end and use a live center. I think that I left the shaft on the long side to allow clearance for the tool space between the tool and center. After turning and finishing the .094 stem I then used a parting tool to part the valve from the stock. Chucking on the .094 dia with the head of the valve in the chuck or collet it was easy to machine the .094 stem to length

 

[awake]

CFLBob,

Looks like it worked - well done. Something to keep in mind - trying to cut this with effectively a form tool can lead to chatter. I don't know the Sherline setup, so don't know if you have another option - but if you can set the compound to the angle, then turn the tool straight, that would let you take a single-point cut rather than a form cut.

 

[CFLBob]

I'm following a technique the Brian Rupnow posted a while back, '16 I think, and he recommends cutting it in thirds. This one is 0.9" long, so I made a mark at 0.9 and 0.6 and 0.3 and cut to those. The Sherline is a micro lathe, 3" over the bed, and only about 1/10 HP, so I take small cuts, like .005 (radius) and just turn the crank a lot. My micrometer says those segments are all about .005 oversize diameter. Brian said to shoot for .003".

This was intended to be a practice piece to get through little problems like I've found. At this point, there's a chance it will come out usable. I might keep it as souvenir if it turns out good.

 

[Brian Rupnow]

The biggest pucker factor is trying to stay .003" to .005" oversize on the stem---all three sections. If you go undersize on any of them, start over again. If you leave more than .003" oversize it seems to take an incredibly long time to sand that down to the desired diameter. One thing I do, before I set up to cut a valve, is to drill and ream a small piece of scrap to the desired diameter, and use it to check the progress of your sanding on the stem. This is one of the areas where your micrometer may lie a little bit. I have, in the past, made valves that when measured with my micrometer SHOULD fit into my valve guides, but in reality were still a bit too large.--Half a thou can make a huge difference to the fit.

 

[CFLBob]

Brian, I took that series you posted back in '16 and made a document in Word, then printed it out to work by. First thing I did was make a tool like the one you show, a 3/4" diameter, 1" long piece of round bar, with an axial hole reamed to .094 - I'm changing all the dimensions to the Webster's smaller valves.

We had company today so I didn't try to start the sanding.

 

[minh-thanh]

All the engines I did: I usually made the valve body a little smaller than the valve seat, which would make the valve and valve seat "easy" to seal.
Especially with Atmospheric Intake Valve , Because the valve is only kept closed to the valve seat by a very very slight force of the spring

 

[CFLBob]

I proceeded slowly with the sanding strip until it appeared that the area closest to the back of the valve (all the way on the left in the pictures above) was staying larger than the sections farther along the stem, meaning the stem was tapered. I tried a narrow file just in that area and was able to reduce the diameter.

I've put a video up on YouTube that shows a test fit of the valve stem diameter checker and the stem on my test valve.



What I'm trying to show is that the valve seems to fit tighter just before the taper about a tenth or eighth of an inch. My micrometer says the valve is undersized there. With the tester around the middle of the stem, it spins easily. Up near the tapered part of the valve it moves but doesn't spin freely.

I have a hard time judging if this is the proper fit.

 

[Misterg]

What I'm trying to show is that the valve seems to fit tighter just before the taper about a tenth or eighth of an inch. My micrometer says the valve is undersized there. With the tester around the middle of the stem, it spins easily. Up near the tapered part of the valve it moves but doesn't spin freely.

I don't think you need to worry about that last tenth of an inch, as the ~0.11" of the valve stem nearest the head will be in the large diameter valve throat , not in the guide.