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Oct. 3, 2008 1:02 p.m. Jensenman SuperDork

ignorant wrote:

nickel_dime wrote:

914Driver wrote:

Jensenman wrote:

Yeah, the tolerances are super tight. I turned a one piece PB for the J-H out of Oilite bronze, the recommended tolerance from shaft to bushing was something like .004.

BWAHAhahahaha! I had a guy make bushings out of oilite bronze and he zinged the things at a zillion rpm; he spun all the oil out of the material.

Yeah, I learned that lesson early on. Ended up throwing the shirt away.

Holding a .0005 tolerance shouldn't be overly hard for an experienced machinist on a conventional lathe. It just takes a careful touch. It's a single setup for the OD and ID. The only PITA I see would be facing the back end to length after parting it off.

2 decimel place length with no surf finish, perpendicularity or flatness. The lenght and face treatment is probably the easiest thing on that bad boy.

I have George's old lathe, it's a humongous South Bend that's probably half again as old as I am. And that's way too damn old. The cross head is pretty loose, I have fiddled with the adjustments but by the time I get it back to tolerances the mechanism is too tight to turn by hand. By being careful, I can keep it close but I always run the risk of boogering up my work piece. If it has to be closer than .002 I'll farm it out.
Oct. 3, 2008 1:49 p.m. 914Driver HalfDork

I wouldn't offer if it was impossible, I know what it's ike to have your hopes dashed. The depth of .001 is cake, do the depth then face off the top to .001, not the other way.

Fee is free, you're family. Those tolerances indicate a 32 finish, also no problem.

As far as temperature, that comes only into play at four decimal places.

You guys duke it out and let me know, I'm at work on Monday.

Dan
Oct. 3, 2008 1:51 p.m. 96DXCivic New Reader

To bad you don't have access to a CNC machine. You could make that no time. I am going to be learning CNC over the this semester at college.
Oct. 3, 2008 2:00 p.m. 914Driver HalfDork

NC is best for the production of many parts, put it in punch "cycle start" and wait. Knocking off one piece only and the programming & set up time kills you. With CNC you still have a window of .0005 thousanths of an inch.

"Feeling lucky?"
Oct. 3, 2008 2:03 p.m. jwc38 New Reader

96DXCivic wrote:

To bad you don't have access to a CNC machine. You could make that no time. I am going to be learning CNC over the this semester at college.

I had a buddy with a wobbly microlathe.. I think it came from harbor freight... that bridge is still smoldering though, cant really talk to him about the project =P I feel that i am going to be spending a lot more time on these boards
Oct. 3, 2008 2:21 p.m. 96DXCivic New Reader

If you have a CAD file the set-up and programming really doesn't take that long.
Oct. 3, 2008 4:52 p.m. 914Driver HalfDork

JThw8, recheck your tolerances; not because I can't hit them but what is the expansion coefficient of brass vs steel? With .0005 at room temp vs .0005 at operating temps, will the thing turn into a mass of red hot metal and a melt down?

Just asking....
Oct. 3, 2008 5:24 p.m. dan_efi New Reader

I don't get the big deal that everyone is making this out to be?!?! Those tolerances are daily duty in any job shop, almost every bearing fit I've done in the last 6 years was +.0004/-0. If I understand the part and it's application properly, it's only an adapter for a pilot bearing? Regular ole 1018 cold-rolled is cheap, available, easy to machine, and will have close enough to the same thermal expansion rate as your crankshaft/flywheel/input shaft. $$$ will probably run you $75-$100 for a one-off. Yes it sounds steep for a couple ounces of scrap steel but gotta cover overhead for a couple hours. Bore, turn, face all in one setup. Can be faced to overall length after parting or part it right to length.

But seriously, am I missing something? You guys are talking like this is a space shuttle part, not an adapter for an engine conversion
Oct. 3, 2008 6:32 p.m. Slippery None

JT,

I am not sure if any one got you covered. I can machine that on a CNC Mori Seiki with no problems. I machine +/-.0002" all day. I will do it for free if I can mail it to you by friday 10th. The catch, I think all I have available is 303SS / 316SS / 6061T65 and maybe some C12L14.

As far as programming that part is so simple I would not even to turn on Surfcam or anything ... it can be programmed right at the machine.

Also they are calling the .435" depth a diameter. I wonder if they put much thought on the rest of the numbers.

Let me know. J
Oct. 3, 2008 7:03 p.m. jwc38 New Reader

Slippery wrote: Also they are calling the .435" depth a diameter. I wonder if they put much thought on the rest of the numbers.
I put the design into e-machineshop and it looked right with that in spite of it being marked as a diameter, probably just a slip up.
Oct. 3, 2008 7:12 p.m. JThw8 Dork

Guys thank you to everyone for all the input. Tetzoe/JWC38 is the guy this is actually being made for. I was steering him over here because he needs to learn the grassroots way.

My personal feeling is the tolerances aren't that exact, its just an adapter for a pilot bearing, as others have said there will be variances in the bearing and the other parts I think as long as it holds the bearing snug it would work.

Slippery, dude, Im a computer geek and a backyard hack you totally lost me other than I guess you are telling me types of material :)

I guess all I can say to all the great offers of help, guidance and questions, if you needed to adapt a pilot bearing for your engine swap what would seem suitable to you?

Thank you again to everyone, the ideas discussion and offers of help are exactly what makes this place great and why I pointed JWC38 to join us, hes building a nice grassroots 944/LS1 toy and I know he will earn alot from the group.
Oct. 3, 2008 8:05 p.m. 914Driver HalfDork

Looks ike dan_efi can pull it off for you JT. Step on up.
Oct. 3, 2008 8:30 p.m. JThw8 Dork

914Driver wrote:

Looks ike dan_efi can pull it off for you JT. Step on up.

Not me that has to step up its JWC38 :) I just started this thread on his behalf while he was trying to get login issues worked out.

I do appreciate everyone's input and offers and we'll make sure it works out.

As always if there's anything I can offer in return in one of my areas of expertise just holler (I do some killer vinyl graphics for instance)
Oct. 3, 2008 9:06 p.m. ignorant SuperDork

303 SS = Stainless 316 SS = stainless steel

6061T65 = aluminum (pretty good grade the T-65 is the artifical aging which is hardness)

C12L14 = cold rolled steel?

My materials is weak, except for stainless as I worked in a food plant for a bit.
Oct. 3, 2008 9:20 p.m. porksboy HalfDork

914Driver wrote:

Jensenman wrote:

Yeah, the tolerances are super tight. I turned a one piece PB for the J-H out of Oilite bronze, the recommended tolerance from shaft to bushing was something like .004.

BWAHAhahahaha! I had a guy make bushings out of oilite bronze and he zinged the things at a zillion rpm; he spun all the oil out of the material.

My father would heat up the part then put it in boiling motor oil. Said it would put oil back in. He did this on pilot bushings more than once with no problem. Old depresion era farm boy. :)

I cant imagine the tolerances being that tight, Most pilot bushings I've dealt with were an interferance fit in the end of the crank. They would go in with varying degrees of resistance so I would think the I.D. would change with crush?
Oct. 3, 2008 9:31 p.m. dan_efi New Reader

914Driver wrote:

Looks ike dan_efi can pull it off for you JT. Step on up.

sorry, retired at 25! actually.... left the trade this fall to get into mech eng tech program.
Oct. 3, 2008 11:39 p.m. Jensenman SuperDork

Pilot bushing = tap fit into crank (around .002 OD tolerance), .004 from tranny shaft to bushing. I got lucky, on my second attempt the OD was .001 larger than the crank opening and the ID was .004 larger than the shaft. It tapped nicely into the crank, stayed in just fine. Some folks howl, say it won't last as long as a needle bearing but so what? So it only lasts 80K miles, at the current rate the car's racking up miles my great grandkids will be the ones worrying about making a new pilot bushing.
Oct. 4, 2008 12:12 a.m. jwc38 New Reader

well, beggars cant be choosers, If any of you MEs care to help me out and need some help with electrical stuff I do happen to be an EE Ill take anything at this point!
Oct. 4, 2008 7:46 a.m. 914Driver HalfDork

dan_efi wrote:

914Driver wrote:

Looks ike dan_efi can pull it off for you JT. Step on up.

sorry, retired at 25! actually.... left the trade this fall to get into mech eng tech program.

So all the chatter about how easy it is was just talk?

Where are you taking the MET courses? After many years as a machinist and then toolmaker doing prototype and R&E weapons systems, I jumped over to Materials Engineering Tech. I do failure analysis, investigate coatings problems that kind of stuff. There's money in the NDT field also because qualified people are not common. Certification takes time but worth the investment.

Dan
Oct. 4, 2008 10:22 a.m. dan_efi New Reader

914Driver wrote:

So all the chatter about how easy it is was just talk?

Sorry if I came across that way :(

I'm taking the course at the Saint John campus of New Brunswick Community College.
Oct. 7, 2008 8:38 a.m. 914Driver HalfDork

Where would you like it sent?
Oct. 7, 2008 10:16 a.m. JThw8 Dork

Looks great Dan! By now I belive Tetzoe/JWC38 has sent you his addy. But PM me with your's and I'll send along a little thank you for helping out a GRM newb.

And I'll kick his butt into posting a little more about this project of his since its a pretty cool one.

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