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View Full Version : A tricky bushing...how to do it?



torker
05-05-2006, 02:29 PM
Hey guys!
I just bought this bushing for the spindle in my Totota.
$67...I can make it for peanuts...but I don't know how to turn the grease grooves inside. I'm betting I can turn the ones on the face no problem with a 4 jaw but the inside ones have me stumped.
Any ideas....
http://img.photobucket.com/albums/v210/torker/dae96daf.jpg
http://img.photobucket.com/albums/v210/torker/e626ea68.jpg
Thanks!
Russ
**Note** I used a piece of wire to copy the groove twist inside this bushing and it's about 1 turn in 4"...or so (hillbilly measurin) My lathe doesn't even come close to this for threading (4tpi)

IOWOLF
05-05-2006, 02:46 PM
I believe they were cast into the rough casting before it was machined.

torker
05-05-2006, 02:52 PM
Jay...good idea but I just looked (after your post) with a magnifying glass.
There are definite cutting marks on all the grooves.
A CNC lathe would cut these no problem. I no have dat!
Russ

IOWOLF
05-05-2006, 03:03 PM
I am sure they did it B4 CNC tools.

thistle
05-05-2006, 03:12 PM
the grooves inside could be done with a dremel or die grinderwith a carbide bit and a steady hand i should imagine.
just did a similar job on some bronze bushings

plastikosmd
05-05-2006, 03:13 PM
a shaper with a spin index/dividing head and some gearing/coordination between the turn and cutting stroke maybe?

scott

japcas
05-05-2006, 03:14 PM
We've made bushings at work like that except they had an inside diameter of probably 5 to 6 inches. We do it one of two ways depending on how fast the customer needs them. The quick and dirty way is a die grinder with a carbide ball grinding bit. We usually lay it out with a magic marker and just gage the depth by eye. You'd be surprised how good you can make them look with a little practice. The other method is using a Cincinatti universal mill with the proper gear train setup on the dividing head. The mill drives the dividing head when the x axis feed is engaged and it rotates the part as it goes through. When you get one flute finished you rotate the dividing head 180 degrees and start the next flute. You have to tilt the vertical head over so the tool clears the front of the part. We use a end mill extension with an ER collet to hold the ball endmill. It makes a good looking job but it's time consuming to set up.

Mike Burdick
05-05-2006, 03:19 PM
Russ,

Just a thought...

Can you 'rearrange' any of the lathe's gears on the gear train that will get you close? For example, switch two gears around so it speeds up the RPM's to the quick change box. I know you won't have much of a choice but who knows...

tattoomike68
05-05-2006, 03:39 PM
I have made grease groves like that by turning it slow, and just hand feeding in and out. It is not that tough to do, it takes less than 10 seconds.

Practice it , I had to do a few dozen and they came out great. its just for grease. If you want to keep the grease from comming out one of the ends dont cut it all the way, set a stop or just put a marker mark on the borring bar.

peice of cake, you can do it. :)

SGW
05-05-2006, 03:47 PM
What Mike said....

My South Bend has a 20-tooth stud gear and a 56-tooth screw gear, normally. Swap those and I can get *REALLY* coarse threads....

If you try that stunt though, you'll almost certainly want to turn the spindle by hand. Make a crank handle to fit the outboard end of the spindle.

Rustybolt
05-05-2006, 03:55 PM
Atlas Lathe had/has gear ratios for turning 1 thread or 1/2 thread per inch. Index screw machines had threading cams that would allow up to 1/8 thread per inch going forward and back(think of guide traverse on a bait casting reel.)All for just such a purpose.

Peter N
05-05-2006, 04:37 PM
**Note** I used a piece of wire to copy the groove twist inside this bushing and it's about 1 turn in 4"...or so (hillbilly measurin) My lathe doesn't even come close to this for threading (4tpi)

I don't know what the application is, but would it matter if it had twice as many grease grooves (8TPI instead of 4TPI)?

If it doesn't matter then I would set the lathe up for 8TPI, clamp a dremel or hand drill with a carbide burr on the saddle, set depth of cut, engage the leadscrew and with the motor off hand crank the spindle and cut to half the depth of the bore, turn the part round and then do the other end.

You end up with twice as many grooves, which may or may not be good depending on the application of the part. Just a theory but I think it would work fine.

Peter

CCWKen
05-05-2006, 05:30 PM
I thought he said 1 turn in 4"--That's NOT 4tpi, that 1/4tpi. I'd darn sure turn the chuck by hand. For me, 8tpi at dead slow is a bag of worms. I can't imagine running 4" in one turn of the chuck! :eek:

There's special broaching rams that do that. They probably make a bushing in a couple of seconds.

pcarpenter
05-05-2006, 05:43 PM
You can probably *buy* it for peanuts too. I don't know what the bore is, but McMaster has them groved up to 1" and without groves much larger than that.

The grove is not critical in dimension...just a grease groove. How about a dremel tool or die grinder? You could add your own grease grooves to a $5-10 bushing made of your choice of bronze types.

paul

Mark McGrath
05-05-2006, 05:56 PM
Before cnc there were special oil grooving lathes for doing this.Some toolroom lathes had attachments that did it as well.
Mark.

torker
05-05-2006, 08:27 PM
Thanks guys!
I thought of the dremel/die grinder idea but I was thinking there may be a demand for these.
BTW...they are metric for the Toyota spindle. All this does is center the axle as it turns. There is no weight bearing and it's not part of the steering etc.
They don't last very long and $67 Cnd is too much in my book.
The ID is 1 5/16" or so.
I was sort of thinking they should look all the same and was lost on how to do this.
I've been thinking that I can make a spiral rod and a follower for one of my spin indexers. Course you'd have to have one for either hand of twist to replicate the factory bushing.
Then why not mount a shaper type of cutter to a piece of thick plate at the proper cutting height.
Mount the spin index in front of it.
Have a three foot long lever behind the spin index with a bearing that would push on the rear of the indexer. The bearing would allow it to spin easily.
You could mount the cutter so it would swing in and index it with stops to control the cut depth.
Yes...this groove is 1 turn in 4".
I don't know if it would hurt to have a 4tpi groove but I'm sure there is a reason why they use such a course pitch.
Just kicking around ideas. Sticker shock does that to me.
I made new bushings for my winch. They wanted $90 for the two. Mine cost $12 for material.
Nope...I'm not smokin dope either :D
Russ

japcas
05-05-2006, 09:22 PM
I'm not an engineer but I believe I know why the groove pitch is like it is. The idea is to get grease across the bushing but if they put a straight groove in that is parallel with the bore the bushing would probably wear right around the groove which would cause an out of round condition in the bushing. Now, if they put a slight twist in the groove the bushing will wear more evenly as opposed to just one area. If you put a 4 TPI groove in the bore, you would be decreasing the amount of surface area in the bushing which would also decrease the life of the bushing. Just my thoughts on the matter, I'm no expert.

torker
05-05-2006, 09:36 PM
japcas...that makes sense to me. With 4tpi you wouldn't have as wide of a groove either, therefore it wouldn't hold as much grease.
But then again you would have more linear area for grease with a longer but narrower groove. Hmmm...are we opening a can here?

Weston Bye
05-05-2006, 10:03 PM
I once watched a machinist cut such grooves in a similar sized bushing with nothing more than a hammer and chisel. Did a good job, too. Can't remember where he was from, but he spoke with a German accent.

Rich Carlstedt
05-05-2006, 10:13 PM
Not sure of the application, but those grooves are not standard by any means.
Most grooves are for retention of grease or oil.
To do this requires Trapping the lubricate within the groove,
and making sure hydrodynamic forces do not remove it.
Running a groove to the face is a real No-No for this application.
Both face and bore grooves do not contain the grease "as shown in the pics"

I am not trying to be argumentive, just pointiing out a major engineering fault.
Hard to believe a Car maker would do this, Unless, the grease comes from one side only, and needs to be delivered to the other side.
Using it as such is the reason for poor life....Sorry for the bad news.

Rich

lane
05-05-2006, 10:33 PM
We use to cut the grease groves by hand run the lathe abour 1 r.p.m. crank hand wheel on carrage by hand following black marker lay out line. I have done them as small as a 2 inch bore.

Arcane
05-05-2006, 10:38 PM
If "there is no weight bearing and it's not part of the steering etc" why worry about having grooves at all? Just make the part, and use a high quality grease (I recommend Texas Refinery Corporation brand) and see how it works. Lots of bushings don`t have the grooves and work just fine.

madman
05-05-2006, 10:41 PM
Cam attachment on a old lathe does the lube grooves. I build stuff like that in the die shop occasionally.

torker
05-06-2006, 01:01 AM
Not sure of the application, but those grooves are not standard by any means.
Most grooves are for retention of grease or oil.
To do this requires Trapping the lubricate within the groove,
and making sure hydrodynamic forces do not remove it.
Running a groove to the face is a real No-No for this application.
Both face and bore grooves do not contain the grease "as shown in the pics"

I am not trying to be argumentive, just pointiing out a major engineering fault.
Hard to believe a Car maker would do this, Unless, the grease comes from one side only, and needs to be delivered to the other side.
Using it as such is the reason for poor life....Sorry for the bad news.

Rich
Rich, what you say makes sense. The "idea" here (I think) is to pack the innerds with a free flowing moly grease and let the birfield end of the axle keep pumping the grease into the bushing.
The only time the bushing is actually used is when the hubs are turned in and the t-case engaged.
I can drive for a million miles and never use the bushing...if it's in two wheel drive.
The front drive axle spins inside of this bushing and is very important as it protects the life of the seal as well as lining up the short stub to the drive hub.
Mike...what he heck does this cam thing look like or how does it work?
Russ
(Can't wait til Forrest sees this)

darryl
05-06-2006, 02:53 AM
After thinking about this for a few minutes, here's a way I might try it- make a boring bar that you will mount in the chuck. On the end of that, cross drill a hole for a piece of drill rod, which will become the cutter. Tap that hole about halfway through and insert a setscrew. The piece of drill rod gets adjusted by this setscrew. Now drill and tap for another setscrew that can hold the drill rod in position. This hole would be in the end of the bar, and maybe off center to be able to grip the drill rod in a suitable spot along the inserted length of it.
Anyway, one trick is in the shape of the cutter that's mounted in this bar. Grind a chisel tip on the drill rod piece, leaving a bit of a flat. It'll look like a screwdriver tip at this point. Then grind a slight arc on the flat to match the id of the bushing you have. Grind on one side of this tip to create the cutting edge. When you grind the arc, make it such that there's some small relief behind this cutting edge. Now when you mount the cutter in the cross hole, angle it to the same angle as in the bushing you bought. Mount the bushing you make on the crosslide with a suitable fixture, centering it of course. As you turn the spindle by hand, and bring the bushing up to the cutter, the cutter will tend to most easily follow into the bushing along the groove it makes at the angle it's set to. You'll have to co-ordinate the movement of the spindle with the travel of the saddle to facilitate the start of the groove. This you would do by feel, and of course it's a two hand powered operation.
The cutter would need to have a flat ground on one side where the setscrew holds it, and this flat keeps the angle from changing as you reposition the cutter (using the inline setscrew) for multiple passes. A second flat ground on the cutter would be to hold an equal but opposite angle for turning the other grease groove. You'd be turning the spindle the opposite way for the second groove, but still bringing the saddle the same direction , probably towards the chuck.

I think with the angle the cutter would have to be set to, that the feel of this operation should be easy to pick up.

Putting a slightly different angle on this idea, think of those pump type screwdrivers- push down and one full stroke turns the tip a few turns. Flip a lever, and it goes the other way. I can't remember the name of these, but you could use the guts to make a leadscrew of sorts to move the carriage along precisely keyed to the rotation of the spindle. I think the helix angle is pretty close to the angle of those grease grooves.

Oh, yeah I remember, it's called a Yankee screwdriver.
If you could use the shaft out of one, maybe you could dispense with the cutter having to be ground to be a 'pin' following in it's own groove.
Well, there's a couple more ideas for ya.

torker
05-06-2006, 07:49 AM
Darryl. I forgot about the Yankee screwdriver. Used to have a very good one actually.
I think you are right about the helix angle on those, it is close to the same.
Hmmm.... couple that idea with Kens idea about the broach.
Maybe I was thinking the wrong way. Maybe the bar should do the cutting and twisting while the bushing is captive and immobile.
Such a simple little thing but so hard to make like they do.

doug931
05-06-2006, 02:37 PM
Russ, You already have half the solution in your hand. Use the grease grooves in your old bushing to guide a boring bar mounted on the tool post.A cross hole in the boring bar would hold a cross pin. Adjust stick out to engage the grease grooves. Push the boring bar with a lever and a thrust bearing( to allow rotation). Owens manual shaper could be adapted for this.
not to steal your thead, but have you heard of my new Ikega Lathe,20 by 60. Doug

torker
05-07-2006, 08:14 AM
Doug, I was thinking the same thing but wondered how long the bronze grooves would last if used for a guide. No doubt long enough to make a few.
I was also thinking of somehow using the spindle from an old bicycle. The rear one that uses the helix groove as part of the brakes.
No...I didn't hear about your new toy!
The name tells me it isn't a real old clunker. So what you got?
Russ

Guido
05-07-2006, 12:32 PM
Boy, this thread brings back old and violent memories.

It was my first attempt at 'repacking' the New Departure brake on my bicycle which probably kicked me over dead center, regarding mechanical aptitude. I couldn't believe it when the brake was back together, and worked. Pretty slick the way that helix worked and the brake discs had to be alternated between teeth and no-teeth.

The Yankee screwdriver was a no brainer, but the kids were making a nice firecracker on the 5th of July when they discovered heat from friction will detonate blackpowder. A piece of Roman candle, packed with the remains of all their dud firecrackers needed a fuse, mounted in the side of the cardboard tube Roman candle: a la Cherry Bomb. No problem, squeeze the now packed Roman candle tube in the vise and use a Yankee drill to make the hole for the fuse.

They were in the neighbor's garage, blew one set of fingers down the side of Mom's new, white Olds, cardboard pieces acting like shrapnel, fire blast took all eye lashes, brows, hair, plus four broken ear drums.

The only thing positive was that the one kid was using his left hand to guide/steady the drill bit, and not his right hand.

G