Author Topic: Rupnow Overhead Cam-Air Cooled  (Read 35375 times)

Offline Brian Rupnow

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Re: Rupnow Overhead Cam-Air Cooled
« Reply #30 on: February 01, 2017, 09:28:44 PM »
It's a whole new world running a lathe with a DRO on it. First observation is that no matter how well placed the display unit is, you can't watch both it and the tool tip at the same time. You can watch one, or you can watch the other, but there is no way in Hell to watch both at the same time. When the lathe is in "power feed" mode, those numbers change awfully quick. The first pass isn't too bad, because there is no shoulder on the part being turned. By the time you get to the third pass, there is a pretty good shoulder formed on the part, so you definitely don't want to over-travel. Working with a DRO is a lot like that old-time religion.--You just got to have faith!!! That is a piece of grey cast iron in the chuck, and I'm taking 0.020" depth of cut at about 260 rpm. with a brazed carbide tool. The o.d. on that cast iron is crusty, rusty, and kind of horrible. I chuck it up in my lathe semi-tight, then use my "bump tool" to bring it to as close as I can get it to running true, then tighten the chuck up all the way. the material is larger than the bore in my spindle, so I put a center countersink in the non chuck end and then run a dead center in my tailstock chuck to assure that it doesn't come bounding out of the chuck and chase me around the room. I had that happen once, and it is a life altering event!! I leave the lathe in "power feed" until I see the last 0.100 of travel come up on the display, then kick out the power feed and finish the travel with the big wheel on the front of the apron.

Online crueby

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Re: Rupnow Overhead Cam-Air Cooled
« Reply #31 on: February 01, 2017, 10:05:08 PM »
Hi Brian,

That is something I was wondering about on the larger (than my Sherline) lathes with the power feed - when you go to the front handwheel, how far does it travel per full turn of the handwheel? Is it fine enough that you can just use it for shorter cuts?

Chris

Offline Brian Rupnow

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Re: Rupnow Overhead Cam-Air Cooled
« Reply #32 on: February 01, 2017, 10:50:20 PM »
Chris--In one full turn of the handwheel on the apron, the carriage moves 1.18" according to the DRO.  This is a bit weird, but then again, that is almost exactly 30 mm. There appears to be 59 divisions on the wheel, and it is marked as being .020" between each mark, so that seems right.

Offline Art K

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Re: Rupnow Overhead Cam-Air Cooled
« Reply #33 on: February 02, 2017, 01:04:07 AM »
Brian,
My experience with a DRO is that you run it up by eye and move it by hand by the dro. Because you can't really read those numbers as they fly by. The only time I had a part chase me around the room was on a cylindrical grinder. Made a pass checked it ran it in for a finish pass, next thing I knew it hit me in the chest spinning down my arm and hand. would have been fine but for the keyway. Sharp edge on that. Never did figure why it threw it. It was during my last week at that job to.
Art
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Offline Brian Rupnow

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Re: Rupnow Overhead Cam-Air Cooled
« Reply #34 on: February 02, 2017, 02:42:07 PM »
This morning we have a cylinder. The fins are all the same width, and trust me, ---that's a good thing!!! I have a tailstock live center that is just barely large enough to act as a bull nose to prevent the outboard end of the cylinder from moving under the side pressure of cutting the fins. I always drill the center bore out before cutting fins. Start with a 3/8" drill and move up by 1/16" increments until I get to 15/16", then drill thru with a 31/32" drill, then ream to 1" finished bore. I cut the grooves between fins .094" wide x 0.345" deep using a 3/32" HSS parting off blade and the lands between grooves are .094" wide. The lathe was turning at 230 rpm. and I cut the fins almost full depth with automatic feed, except for the last .025" which I fed by hand, so as not to overshoot. Although it made a Hell of a racket it got the job done right smartly.

Offline Brian Rupnow

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Re: Rupnow Overhead Cam-Air Cooled
« Reply #35 on: February 02, 2017, 06:53:33 PM »
I have a question, and it's a hard one. Fortunately, I also have the answer to the question. On a cylinder like the one in the drawing, after you have tapped the four holes in one end, how the heck do you turn it around and put the tapped holes in the other end in the same rotational orientation? This is almost impossible to do.-------Unless-----You have a rectangular plate that bolts onto the other end. If you do, you make the rectangular plate, bolt it onto the first set of holes in the cylinder, then hold the plate in the vice so you can tap the holes in the other end of the cylinder, with assurance that the second set of holes really will be aligned rotationally with the first set of holes!!


Online Jasonb

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Re: Rupnow Overhead Cam-Air Cooled
« Reply #36 on: February 02, 2017, 07:00:48 PM »
Why bother making a plate.

Drill and tap the top set of holes, screw the already made head onto the cylinder and then hold the two by the cyliner head using the flat faces of the head to line up the cylinder so you can drill the bottom set.

Or put two studs into opposed holes in one end and line them up to do the other end if you don't heav a head or need teh plate for lower down in the engine

Third option is to make the cylinder and plate all as one from a block of CI then you only need to drill one end anyway

Simples

Offline Brian Rupnow

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Re: Rupnow Overhead Cam-Air Cooled
« Reply #37 on: February 02, 2017, 08:11:49 PM »
Jason--I had to make the plate anyways. It is part of the engine. Regardless of whether you bolt the head on first or bolt the plate on first, you need to have something bolted onto one end to align the part for tapping the holes in the other end.---Brian

Offline Brian Rupnow

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Re: Rupnow Overhead Cam-Air Cooled
« Reply #38 on: February 02, 2017, 08:49:01 PM »
News is not good. The company in North Carolina that sold me timing belts and pulleys 5 years ago mailed them to me. Now they say they can no longer mail things to Canada, and that they want a $50 courier fee for $25 worth of parts.---plus tax---plus customs fee---plus difference in Canadian and USA dollars. I was ready to eat the difference in Canadian/American dollars, but this is a bit too much like robbery for my taste. I'm now trying to source the pulleys and belt from a Canadian supplier.

Online Jasonb

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Re: Rupnow Overhead Cam-Air Cooled
« Reply #39 on: February 02, 2017, 08:54:59 PM »
Pullies should not be too hard to mill the teeth on yourself which would only leave the belt to source.

Offline 10KPete

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Re: Rupnow Overhead Cam-Air Cooled
« Reply #40 on: February 02, 2017, 09:48:54 PM »
That's just amazing. I could see where a company might choose not to mail to Canada (??) but to say they can't...??? Has there been some change in regulations??? That's just maddening!!   :Mad:

Engine's looking really nice, Brian. Can't wait to see it run!

Pete
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Retired, finally!
SB 10K lathe, Benchmaster mill. And stuff.

Offline Brian Rupnow

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Re: Rupnow Overhead Cam-Air Cooled
« Reply #41 on: February 03, 2017, 12:09:23 AM »
I think I'm going to have to do something to keep those yellow "lifters" from rotating. Ordinarily, you would want them to rotate a bit each time the cam lobe "wiped' across the top of them to equalize any long term wear pattern. In this case however, if they rotated it would make the valve rotate----and we don't want that. Valves like to settle into one spot and stay there, and that is where they will "wear in" a seating position and seal tighter than a ducks butt. If they rotate a bit with every "wipe" of the cam lobe, then they are going to not seal consistently and will probably quickly wear away the valve seat area on the valve cage.

Offline 10KPete

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Re: Rupnow Overhead Cam-Air Cooled
« Reply #42 on: February 03, 2017, 03:37:11 AM »
No, no, no... valves should rotate while operating. For years many engines had a separate valve rotator mechanism to make sure they did turn a bit each stroke.

This all depends on a few things though: concentricity between the valve seat and valve guide, and concentricity between the valve stem and the seat on the lip. Without that, rotation will cause problems. But then you'll have problems anyway.

That's my two cents worth anyway....

Pete
Craftsman, Tinkerer, Curious Person.
Retired, finally!
SB 10K lathe, Benchmaster mill. And stuff.

Offline Ian S C

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Re: Rupnow Overhead Cam-Air Cooled
« Reply #43 on: February 03, 2017, 12:39:30 PM »
Surely there is somewhere in Canada that can supply belts and pulleys,  I'm quite sure that they are even available in NZ.  It seems as if it is getting harder to buy things these days.
Ian S C

Offline gbritnell

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Re: Rupnow Overhead Cam-Air Cooled
« Reply #44 on: February 03, 2017, 01:39:14 PM »
Hi Pete,
I think what you're referring to is lifters should rotate. A valve operated by a rocker arm and pushrod won't rotate.
gbritnell
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