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Sat Sep 03, 2022 6:17 am

chrisflstf wrote: Ok, Here is a machining question/tooling question. How can someone with a drill press, small X & Y table, dremel, files, welder, saws, etc make something to do a simple 30 degree backcut on 4 intake valves? The width of the cut needs to be about .025” My mind draws a blank

I watched a guy on you tube hand hold a dewalt against a small bench sander to do it, and although, it wasn’t bad, no way would I try that

Yeah I can send the valves out or find a local head shop, but I like to experiment when possible.

I have seen guys chuck up a grinder in a vice and spin a valve in the chuck. I wouldn’t do it to cut the face which needs to be dead nuts concentric to the stem, but a back cut doesn’t have to be particularly accurate, so it works.

People have even done back cuts with a drill press and file by eye.

Sat Sep 03, 2022 7:00 am

chrisflstf wrote: Ok, Here is a machining question/tooling question. How can someone with a drill press, small X & Y table, dremel, files, welder, saws, etc make something to do a simple 30 degree backcut on 4 intake valves? The width of the cut needs to be about .025” My mind draws a blank

I watched a guy on you tube hand hold a dewalt against a small bench sander to do it, and although, it wasn’t bad, no way would I try that

Yeah I can send the valves out or find a local head shop, but I like to experiment when possible.

Put the valve in the drill press chuck. Rig up some way to hold and clamp your dremel in the vice at 30deg. Get a new 3/8 diameter cylinder shaped stone for the dremel.

Leave the vice loose on the drill table. Turn on the chuck and the dremel, and slowly work the vice into the valve by hand. It won’t take much, and hardly any pressure. The weight of the vice should be plenty to keep it all steady.

Practice on a junk valve first.

Brian

Sat Sep 03, 2022 7:10 am

Quote: Put the valve in the drill press chuck. Rig up some way to hold and clamp your dremel in the vice at 30deg. Get a new 3/8 diameter cylinder shaped stone for the dremel.

Leave the vice loose on the drill table. Turn on the chuck and the dremel, and slowly work the vice into the valve by hand. It won’t take much, and hardly any pressure. The weight of the vice should be plenty to keep it all steady.

Practice on a junk valve first.

Brian

It just dawned on me the drill press table tilts ( forgot about that). So there is the answer to my 30 degree dilemma. Valves are cheap, so Imma gonna give it a try. Thanks! :D

Sat Sep 03, 2022 10:30 am

Those are all the wrong tools for working on valves - :lol:

Don't treat your precision parts like that. If you don't have the proper tools, leave them alone.

At minimum, you need a lathe to do the back cut. Accuracy is key - if your valves are all different shapes, how do you expect them to flow properly? Those angles have to be similar valve to valve.

The best way is just buy you a proper valve grinder and seat grinder. They are all over Ebay -

Sat Sep 03, 2022 1:15 pm

The back cut on a valve isn’t super critical. I say go for it. Try it on a junk valve first. As long as you keep the grinder clamped steady so the angle doesn't drift while it’s running, you will be fine. The runout of the chuck on the drill press shouldn’t be more than 5 thou or so. Heck, it’s probably as good or better than the antique black and decker valve grinding machines that are all over the place.

Sat Sep 03, 2022 5:20 pm

The most worn out valve grinder will still be way better than any handheld grinder of any brand.

But hey - try the handheld grind back cut and show pics here. Maybe we can see how good one's dexterity is. Should be fun to watch.

Maybe post a video - :D

Sat Sep 03, 2022 5:57 pm

Here u go. Not hand held, actually clamped good in the jaws. No way for the dremel, lol. I may experiment swapping it around some , before i test it out. And i will need to figure out measuring the cut angle as the adaptor has a fair amount of play in the chuck. But i can compensate, if i know the cut angle.

Sun Sep 04, 2022 7:40 am

Nice work. I am sure that will work well. May be a little slow, but should work fine. Valve grinders are quicker and are easier to get a consistent width of the back cut. However, with a bit of time and care, you can get good results with the set up you have.

I actually know a guy who reground his worn out R8 spindle taper in his Bridgeport mill by clamping a die grinder in his mill vice, angled the head to match the taper, then with the mill and die grinder running, fed the grinder into the spindle. Turned out great. He checked it with bluing and a good R8 arbor. Even blue coverage everywhere. Took his spindle runout from about 0.001” inches to about 0.0002. Not perfect, but probably better concentricity than most collets on the market today.

Just goes to show that you can get good results with basic tools, a little ingenuity, and patients. :wink:

Sun Sep 04, 2022 8:26 am

My version of adding a DRO, lol. :D

Sun Sep 04, 2022 2:05 pm

Your valve grinder setup is very far from optimum, but there are some good ideas in there too.
I like the idea of the valve held vertically, and using the angle meter. :D

Mon Sep 05, 2022 5:31 am

I don't think that angle attachment is gonna be fast enough to do grinding w/ that iddy-biddy stone. Maybe use a Dremel tool instead?

I can see a toolpost grinder bolted to the table and just swing it over to the valve to remove material. Maybe a 2-inch wheel?

For grinding, the chucking head only needs to spin very slow. But the grinder wheel needs to be spinning pretty fast if it is small diameter.

Mon Sep 05, 2022 6:53 am

Thanks for the input. I was wondering about the speeds. Ive made a couple changes, so just waiting for some valves to try out

Mon Sep 05, 2022 7:44 am

oprn wrote: My lathe is an old belt drive South Bend with a drawer full of gears for threading. It’s well used and could use some work but I wouldn’t be without it!

I have been torn between an old quick change south bend 13, and a Miller 220 Multimatic welder. The number of times I have had use for a lathe is, well… I can’t count. Those old south bend lathes definitely lack some features standard on modern lathes, but boy do they have a nice surface finish. Something about the flat belt drive and plane bearings makes them super smooth.

However, I have also wanted a welder that can do more than steel. The multimatic would be great away from home because I would only have to move one machine to mig, stick, or tig. The 220 also does AC tig. I would love to learn aluminum welding… again, the number of times I have wanted to do that…

it’s pretty much a dead heat between the two.

Mon Sep 05, 2022 4:55 pm

He are some pics of my Rung Fu RF-31 mill that I use to cut a case for bigger cylinders and to deck the case.

Thu Sep 08, 2022 2:42 pm

Well, My experiment to back cut valves didn’t go well. The stone does not leave a very smooth finish. I think its wobble in the spindle of the stone attachment tool
( right angle drill adaptor). My 30 degree angle seems right on tho

Cut on left, virgin on right

So next stop – machine stop. But hey, don’t know what will work until you try

Thu Sep 08, 2022 2:56 pm

chrisflstf wrote: Well, My experiment to back cut valves didn’t go well. The stone does not leave a very smooth finish. I think its wobble in the spindle of the stone attachment tool
( right angle drill adaptor). My 30 degree angle seems right on tho

Cut on left, virgin on right

So next stop – machine stop. But hey, don’t know what will work until you try

The cut doesn't need to be super smooth. The valve isn't sealing anything there, just getting it out of the way of the air. I actually prefer them super rough, just like my ports. :lol:

Lap them to show where the seats land, and send them up here. I will roll out the 1930's Sioux valve facer, and toss a back cut on them for you.

Brian

Thu Sep 08, 2022 4:59 pm

chrisflstf wrote: Well, My experiment to back cut valves didn’t go well. The stone does not leave a very smooth finish. I think its wobble in the spindle of the stone attachment tool

Correct. You need precision bearings and a well dressed grinding wheel, and a better chuck too. Best way to learn is try

Thu Sep 08, 2022 8:21 pm

volk263 wrote: He are some pics of my Rung Fu RF-31 mill that I use to cut a case for bigger cylinders and to deck the case.

Nice!! This is super interesting. How did the case bores come out? Very nice way of mounting, but did having just 1 hold down on each side keep it tight enough?

Also, i see that you have the DRO installed, Is your DRO X axis slide reader on the back side of the table? Im curious how you mounted it.

Fri Sep 09, 2022 7:14 pm

Cylinder bores come out good. You have to keep the runout in the spindle bearings checked and adjust the cutters according. Yes one hold down on each side is plenty. The scale is on the back side of the X axis. The Rong Fu mill comes with the mounting holes tapped for this brand DRO it is a simple bolt on

.

Sat Sep 10, 2022 6:48 am

Where do you buy those giant 1 x 2 x 3 blocks?