Models for grinding HSS Lathe Tools

mickri said:
Order some fine belts and be done with honing. Not worth your aggravation.
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Doesn't seem to be a skill that I have at the moment. Not for a lack of trying. But need to move on.

Red Label Abrasives has a fine ceramic grit belt assortment that I will get. [P180, P240, P320 & P400] Should be fine for what I do.

For what it is worth, the tool bit cut ok with some expected chatter on my 6061 test piece on my mini-lathe. I hand turned the chuck for the last 0.010" depth at 0.001" depth steps and the finish came out chatter-free enough. I can still see it, but I believe the o-ring should seal on that. The surface where the 124 o-ring is now, is much better than the one on the right. Looks like I should have cut deeper, if I look at the o-ring. (Maybe even wider as well.)

The real workpiece is on my G0752Z, waiting for this bit. The valve design doesn't look like this and has more support for the o-ring on the left side. Just playing around a bit so that I can learn on a non-critical piece.
PXL_20220425_193431698.jpg
 
Oring grooves should have a flat bottom with radii in the corners, so the material can be compressed slightly and has space to move in.
Whats wrong with a 2mm parting blade for grooving?
 
fitterman1 said:
Oring grooves should have a flat bottom with radii in the corners, so the material can be compressed slightly and has space to move in.
Whats wrong with a 2mm parting blade for grooving?
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Not disagreeing with you at all.

The o-ring is not seated against a right cylindrical wall surrounding the piston. The piston and o-ring seal against a tapered conical surface. Sort of like this picture. I have no idea why the valve is designed this way, but I merely want to copy the piston warts and all. The valve is designed to prevent outside contaminated water from entering the indoor potable water system. Rather copy it than become creative, for this one part.
valve_n_seat.jpg
Kind of a quick and dirty addition of the conical seat for the o-ring.
 
Thr reason I ask is because it takes a reasonable amount of effort to compress an oring to create a seal thats watertight.
If something is just seated atop an oring there is no guarantee of a seal occurring.
 
fitterman1 said:
Thr reason I ask is because it takes a reasonable amount of effort to compress an oring to create a seal thats watertight.
If something is just seated atop an oring there is no guarantee of a seal occurring.
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The piston is forced upwards by the water pressure, about 45 pounds/square inch to seal the o-ring. This is part of a commercial and approved backflow prevention valve, pretty sure it has been engineered correctly. There is about a 5 pound spring (wild guess) that pops the valve open if indoor water pressure is lost. This is supposed to prevent irrigation water from re-entering the potable water system. Which is why I am copying it, rather than changing it.

Here is a rough rendering of the spring pushing down the piston face. Think it is tapered this way.
piston_seat_oring_spring.jpg
 
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Gotcha, in other words it is a one way check valve in hydraulic terms.
 
Going to be machining some bearings out of delrin for a friend. The bearing are around 2.375 OD and 1.911 ID. 1.25" long. I will be rechecking all of my measurements this weekend. The bearings are for a rudder shaft on a Santa Cruz 27 sailboat. I have never worked with delrin before.

I will be starting with 2.5 OD 4" long rod held in a 3 jaw chuck. Plan to turn the OD first and then bore the ID. I could do it the other way too. ID first then OD. Makes no difference to me. I would like to bore all the way through. That way I can test fit the bearing on the shaft without removing the bearings from the chuck

Looking for suggestions on clearance and rake angles and speeds and feeds.
 
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