Help needed with making a special reamer

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Help needed with making a special reamer mike.crossfield 01-06-2008
Posted by on January 7, 2008, 4:15 am
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> mike.crossfi...@virgin.net wrote:
> > I need to make a special reamer, and any advice from the group would
> > be much appreciated.
>
> > I've been asked by a friend to ream the oilite bushes to size in the
> > rear suspension arms of a classic Mini Cooper. =A0For those unfamiliar
> > with Minis, each rear suspension arm (cast iron) has two bearing
> > points about 6 inches apart. =A0One is fitted with a needle roller, the
> > other with a thin wall bronze bush. =A0A ground spindle fits the two
> > bearing. =A0From memory the needle roller is roughly 15 mm diameter, and=

> > the bronze bush about 20mm diameter. When the bearings and spindle are
> > replaced, it's necessary to ream the bronze bush to size. =A0As I
> > understand it, the hand-operated factory tool has a long pilot which
> > fits the needle roller, with a reamer section on the other end.
> > Needless to say, this tool is VERY expensive, and purchase is out of
> > the question for one job.
>
> > Can anyone offer any suggestions or tips as to how I might go about
> > making a suitable reamer in my home workshop? =A0I have reasonable
> > collection of machines and associated tooling (lathe, mill, T&C
> > grinder etc).
>
> > TIA
>
> > Mike
>
> =A0>
> =A0>
> The quickest and easiest method favoured by manufacturers with this
> scenario is press a 15mm ball bearing through the bush. No pilot
> required. Of course in production they would use a carbide ball due to
> production numbers.
>
> In this case, machining the head of an old pivot to size, with a nice big
> polished radius, well lubricated and then pulled through by the nut will
> do the job also. Maybe a better option, as one can incorporate any clearan=
ce
> required by the sizing.
>
> Before someone raises the spectre of closing the pores of the oilite
> bush over, this has been the factory service advice for sizing the oil
> pump drive oilite bushes in Mopar engines for decades.
>
> Or they can visit:http://www.ballomatic.com/process.htm
>
> Tom
>
> O & OE as regards the grammatical content of this post.- Hide quoted text =
-
>
> - Show quoted text -




Many thanks guys. A great set of ideas here.

First off I will try Dave Baker's well-described solution, mainly
because it means I don't have to make a reamer at all!

If the bushes are a bit tight when installed, I'll finish off with a
ball or ball-end tool as per Tom's suggestion.

Thanks again

Mike


Posted by Dave Baker on January 7, 2008, 4:31 am
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Many thanks guys. A great set of ideas here.

First off I will try Dave Baker's well-described solution, mainly
because it means I don't have to make a reamer at all!

If the bushes are a bit tight when installed, I'll finish off with a
ball or ball-end tool as per Tom's suggestion.

Honestly you won't. It'll take you a day or more to make such a tool, or the
several different sized ones you'll need to actually make to work out how
much material they really shift. You'll ream it with a fixed reamer on the
lathe and tweak it with an adjustable one later or just do it with an
adjustable one from scratch like I would. If you want a tenner on it let me
know.
--
Dave Baker
Puma Race Engines



Posted by Dave Baker on January 7, 2008, 4:22 am
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> mike.crossfield@virgin.net wrote:
> The quickest and easiest method favoured by manufacturers with this
> scenario is press a 15mm ball bearing through the bush. No pilot
> required. Of course in production they would use a carbide ball due to
> production numbers.
>
> In this case, machining the head of an old pivot to size, with a nice big
> polished radius, well lubricated and then pulled through by the nut will
> do the job also. Maybe a better option, as one can incorporate any
> clearance
> required by the sizing.

Apart from the sheer amount of grief making such a set of tackle you really
can't do it that way by hand anyway with any precision. Ball burnishing
needs to be done at some speed and it's particularly important that the
process doesn't stop at any time or you get a ridge in the material. There's
also always some springback and hence some buggering about to find the size
of ball needed to achieve a finished size in the bore.

Then these particular bearings aren't in fact nice soft porous oilite,
they're normal bronze with a lubrication groove and several thou undersize
not just a few tenths. You'd have a hell of a job pulling anything through
them at that amount of fit even if it could swage that much material out of
the way which I frankly doubt. I think it would stand more chance of ripping
the bronze off the steel backing or just getting stuck half way through.

Frankly this is a simple enough reamer job and no need to unduly complicate
it. In fact despite my patent "method" in the previous post if I was given
this to do for only two bushes and little prospect of anything I made up
specially getting used again in the future I'd just adjustable ream them a
few tenths at a time from the end they push in at until the shaft fitted
through cleanly and I'm quite sure it would be as good a job as anyone would
do with the proper tool or a machine ream. Like I said before it ain't
rocket science and a few tenths of clearance one way or the other won't make
a scrap of difference to the car.

Equally it wouldn't take a decent machinist very long to bore out the steel
bush holder I describe and it gives you the comfort of an accurately
fixtured machine ream for all, or at least the vast bulk of the material.
With more than one set to do it's a no-brainer. With only one set to do you
pays your money and makes your own choices.
--
Dave Baker
Puma Race Engines



Posted by Tom on January 7, 2008, 5:36 am
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Dave Baker wrote:

>
>>mike.crossfield@virgin.net wrote:
>>The quickest and easiest method favoured by manufacturers with this
>>scenario is press a 15mm ball bearing through the bush. No pilot
>>required. Of course in production they would use a carbide ball due to
>>production numbers.
>>
>>In this case, machining the head of an old pivot to size, with a nice big
>>polished radius, well lubricated and then pulled through by the nut will
>>do the job also. Maybe a better option, as one can incorporate any
>>clearance
>>required by the sizing.
>
>
> Apart from the sheer amount of grief making such a set of tackle you really
> can't do it that way by hand anyway with any precision. Ball burnishing
> needs to be done at some speed and it's particularly important that the
> process doesn't stop at any time or you get a ridge in the material. There's
> also always some springback and hence some buggering about to find the size
> of ball needed to achieve a finished size in the bore.
>
> Then these particular bearings aren't in fact nice soft porous oilite,
> they're normal bronze with a lubrication groove and several thou undersize
> not just a few tenths. You'd have a hell of a job pulling anything through
> them at that amount of fit even if it could swage that much material out of
> the way which I frankly doubt. I think it would stand more chance of ripping
> the bronze off the steel backing or just getting stuck half way through.
>
> Frankly this is a simple enough reamer job and no need to unduly complicate
> it. In fact despite my patent "method" in the previous post if I was given
> this to do for only two bushes and little prospect of anything I made up
> specially getting used again in the future I'd just adjustable ream them a
> few tenths at a time from the end they push in at until the shaft fitted
> through cleanly and I'm quite sure it would be as good a job as anyone would
> do with the proper tool or a machine ream. Like I said before it ain't
> rocket science and a few tenths of clearance one way or the other won't make
> a scrap of difference to the car.
>
> Equally it wouldn't take a decent machinist very long to bore out the steel
> bush holder I describe and it gives you the comfort of an accurately
> fixtured machine ream for all, or at least the vast bulk of the material.
> With more than one set to do it's a no-brainer. With only one set to do you
> pays your money and makes your own choices.
>
Apparently my solution is beyond your experience or skill levels.
Your rather crude rebuttal certainly indicates thus.

Reaming rocker arm bushes? With an adjustable reamer? Ever heard of a Sunnen
hone?

As an advocate of pilotless, adjustable reamer, reaming, you aspire to
a skill level that I'd prefer not to know about.

Tom



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