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John Stevenson
02-17-2009, 02:54 PM
Thought this might be of interest to anyone who owns a Bridgy vari speed.

This is what happens when the plastic sheave bushings wear.

http://www.stevenson-engineers.co.uk/files/bridgyvari1_2.jpg

Second pic is a bit blurred as I needed to get this done for 5:00pm and it didn't arrive until 1:30

I get about 15 to 20 of these a year, today I got two but the other although a varispeed wasn't a bridgy as it had no pilot bearing.

Main source of wear is on the keyway but if left to knock they take the shaft out and in this case the 20mm pilot bearing was about 2 mm under the standard 20mm.

http://www.stevenson-engineers.co.uk/files/bridgyvari3_4.jpg

Turned undersize to get the transition layer below the new surface, blobbed a bit of weld on and when dry transferred back to the lathe.
New centre cut in with single point tool as they are always bent.

I have a very relieved tool that I use just for this, better pic below.

http://www.stevenson-engineers.co.uk/files/bridgyvari5_6.jpg

Once the centre is in the steady can be backed off and then the shaft is turned and finally polished down to size and the circlip groove put back in.

http://www.stevenson-engineers.co.uk/files/bridgyvari7_8.jpg

Swap to the mill, is it cannibalism if a Bridgy eats one of it's own ??,
and replace the keyway.

A genuine Bridgeport has a 7mm keyway but in this case the sliding key was opened up to 8mm to suit aftermarket sheaves hence the step in the keyway where it meets the fixed sheath position.

So unless you fancy doing this look after your varispeed when it starts making noises.

.

madman
02-17-2009, 03:14 PM
We will just ship it off to you so you can keep eating in that grand Style you are accustomed to (Bangers and Beans) Sounds Good Thanx for the nice Pictures im still trying to figure out how to shrink my pictures down in my new 10 meg camwera and post them LOL im a compooter Retard.

hardtail
02-17-2009, 03:24 PM
Nice repair John.........smile

MM your best bet is to go into the cameras menu and reduce the resolution as small as you can for any pics you think will be posted on any bb's, there will be waaaaay less final editing reqd.........

GKman
02-17-2009, 06:31 PM
trying to figure out how to shrink my pictures down in my new 10 meg camwera and post them LOL im a compooter Retard.

http://bluefive.pair.com/free_computer_software.htm#pixresizertarget Go to this site and download "PIXresizer". Free, super easy to use and works like a champ.

lazlo
02-17-2009, 08:54 PM
Once the centre is in the steady can be backed off and then the shaft is turned and finally polished down to size and the circlip groove put back in.

John, what's involved in the polishing? Is it just cosmetic (i.e., run sandpaper then polishing compound), or are you actually running it on a cylindrical grinder?


Swap to the mill, is it cannibalism if a Bridgy eats one of it's own ??

LOL! Superb job as always John -- thanks for the pictures!

quasi
02-17-2009, 11:30 PM
John, can you give us some details on the welding? Did you weld the shaft while it was rotating in a positioner or ...?

DickDastardly40
02-18-2009, 04:47 AM
Love seeing repair methodology like this, just goes to show the difference between slightly and completely cattle trucked.

John,

How much under did you reduce the diameter before welding please?

Cheers

Circlip
02-18-2009, 05:46 AM
I suppose you realise big John that single handedly you're accelerating the demise of the ri ---replacement industry of one of the American Iron companies?

Regards Ian.

oldtiffie
02-18-2009, 06:38 AM
Originally Posted by John Stevenson
Once the centre is in the steady can be backed off and then the shaft is turned and finally polished down to size and the circlip groove put back in.



John, what's involved in the polishing? Is it just cosmetic (i.e., run sandpaper then polishing compound), or are you actually running it on a cylindrical grinder?


Originally Posted by John Stevenson
Swap to the mill, is it cannibalism if a Bridgy eats one of it's own ??



LOL! Superb job as always John -- thanks for the pictures!

Lazlo.

I have never seen or heard mention of a grinder in or used in John's shop so I guess it was all done in situ in his lathe - but I'd guess with emery paper or "wet and dry" paper and possibly a file - but I'd doubt that he used sand paper!!.

Nice job, nice recovery and nice use of resources and time John

JCHannum
02-18-2009, 08:17 AM
I would suspect the polishing is little more than that, to provide a smooth surface for the vari-speed bushing to slide on, not to produce some imaginary sub-micron finished dimension.

This brings to mind the sheave itself. They usually are destroyed along with the shaft. Do you do anything to restore them as well?

Bill in Ky
02-18-2009, 08:31 AM
What type of weld do you use? You said that they are always bent, does the welding put stress in them too?
Nice work!

John Stevenson
02-18-2009, 02:25 PM
Various replies in no order.

Bill,
As soon as you start welding on a shaft this long and thin [ 28mm ] the weld will pull it. Even if it was straight to start with it won't be when you are finished.
It pays to run beads around the shaft is possible as long lengths will banana shape the shaft, especially if it has a long keyway in.

It's not a worry as you have to single point the centre back true anyway, centre drill will only want to follow the path of least resistance.

JCH,
You can sometimes get away with a new plastic sleeve and broach a new keyway in opposite to the original. The faces never seem to wear bad, only the bores. Someone in the Uk is doing aftermarket sheaves for Bridgeports but I'm not sure who. I sometimes get a new one supplied or like this case just the rotor.

Tiffie,
I do have grinder, it's a Myford MG9, all manual but it does have the internal attachment. I think it was last used about 6 years ago.

Lazlo,
I turn down to about a thou and a bit above then polish down to sixe with some 240 grade abrasive cloth.
It doesn't take much to remove a couple of thou with some decent cloth and you can keep an eye on sizes along the length.

Dick D,
About 30 thou a side just to get the join layer under the final size.

Quazzi,
Because I do this virtually every day I have geared up for this and any expensive equipment is easily recouped.

I didn't want to post pics earlier in light of Torkers fine positioner as I didn't want to upset him with my design which I do assure you predates his motorised one but just in case anyone want to copy this design here's a general picture.
I can supply drawings if needed.

http://www.stevenson-engineers.co.uk/files/positioner.jpg

:rolleyes:

kmccubbin
02-18-2009, 03:21 PM
Thanks for sharing your techniques with us, John. I've learned much from your show-and-tell posts.
Please tell me, how does one machine a weld (or weld a machineable bead)? Every time I've hit a weld with a cutting tool, the result is a dull/chipped/broken tool.

thanks,
Kerry

aboard_epsilon
02-18-2009, 03:29 PM
Thanks for sharing your techniques with us, John. I've learned much from your show-and-tell posts.
Please tell me, how does one machine a weld (or weld a machineable bead)? Every time I've hit a weld with a cutting tool, the result is a dull/chipped/broken tool.

thanks,
Kerry

i suspect he uses hss with a very rounded end on the tool .

all the best.markj

John Stevenson
02-18-2009, 04:51 PM
Just a normal tipped tool with the cheapest TPUN 16 inserts I can get.

I actually make my own tools, not to save money but I have a job to supply 4 types of cutting tools to a customer who sends 4 tools and spare tips out on each machine hire on portable boring machines for the offshore oil industry.

When the machines come back in the tools and tips are always missing, either held back, stolen or just lost. they are chargeable items but he got fed up of supplying 4 tools at 60 to 70 each only for then to go walk about.

I make these commercially and sell them to him in bulk at a lot less than 60 each but still a profitable job.

they are decent tools with tapered pockets to fit the insert exact and they are also hardened and professionally blacked, just like the ones you get from MSC / J&L

I also make some smaller ones with TPUN11 inserts for Gert to sell.

.

oldtiffie
02-18-2009, 05:04 PM
http://www.stevenson-engineers.co.uk/files/positioner.jpg

John, with that epitome of Engineering design and precision manufacture, where are the ABEC 23 1/2 bearings?

Using emery cloth for precision work - what next?? Where are your 0.500 micron (0.5 x 10^-6 metre) indicators and NIST-certified (traceable) Class 0 slip guages and your 1.0 micron micrometer - not to mention the "clean room" with first class air conditioning and multiple banks of super-fine HEPA filters?

And here - endless "Sins" - this just simply WILL NOT "DO":

1. No "Kurt" vise on the mill;

2. No "Wilton" vice on the work-bench; and

3. Using crap Chinese digital calipers.

Etc.

http://www.stevenson-engineers.co.uk/files/bridgyvari7_8.jpg

This is what you've got coming to you:
http://en.wikipedia.org/wiki/Pillory

http://en.wikipedia.org/wiki/Stocks

http://en.wikipedia.org/wiki/Gibbet

And to top it off, for acting as a heretic you've got this lot coming for you.
http://en.wikipedia.org/wiki/Inquisition

Or perhaps you are just simply beyond redemption and will have to be circumcised or "de-nutted" on a BP (or a clone?).

Report back on progress - within 24 hours!!!

aboard_epsilon
02-18-2009, 05:05 PM
TPUN whats that?...
Recommend me an insert that will take interrupted cuts like that without breaking or chipping..and i will get some for myself....they are the job!

all the best.markj

oldtiffie
02-18-2009, 06:37 PM
Mark,

the answer may be here.

http://www.greenleafglobalsupport.com/webapp/wcs/stores/servlet/Product_10001_10001_-1_10260

http://www.greenleafglobalsupport.com/webapp/wcs/stores/servlet/Category_10001_10001_-1_10063_10062

http://www.google.com.au/search?hl=en&q=tpun&btnG=Google+Search&meta=

oldtiffie
02-18-2009, 06:45 PM
Just a normal tipped tool with the cheapest TPUN 16 inserts I can get.

I actually make my own tools, not to save money but I have a job to supply 4 types of cutting tools to a customer who sends 4 tools and spare tips out on each machine hire on portable boring machines for the offshore oil industry.

When the machines come back in the tools and tips are always missing, either held back, stolen or just lost. they are chargeable items but he got fed up of supplying 4 tools at 60 to 70 each only for then to go walk about.

I make these commercially and sell them to him in bulk at a lot less than 60 each but still a profitable job.

they are decent tools with tapered pockets to fit the insert exact and they are also hardened and professionally blacked, just like the ones you get from MSC / J&L

I also make some smaller ones with TPUN11 inserts for Gert to sell.

.

John,

I am waiting for your response for the description of "TPUN" but I guess that covers the cylindrical part of the job.

What sort of end-milling cutter do you use for the key-way?

aboard_epsilon
02-18-2009, 07:04 PM
Mark,

the answer may be here.

http://www.greenleafglobalsupport.com/webapp/wcs/stores/servlet/Product_10001_10001_-1_10260

http://www.greenleafglobalsupport.com/webapp/wcs/stores/servlet/Category_10001_10001_-1_10063_10062

http://www.google.com.au/search?hl=en&q=tpun&btnG=Google+Search&meta=

the links dont work

been to jlindustrial site ...these TPUN 16 inserts are 5.90 each ...not what i call cheap!

all the best.markj

Peter.
02-18-2009, 07:14 PM
RDG are doing them in packs of 10 much cheaper though.

John Stevenson
02-18-2009, 07:41 PM
Ignore the J&L catalogue price, ring up and ask what their best deal is.

I get real good deals but I buy 50 boxes at a time, that's 500 inserts even on casual sales you should be able to get about 2.50 an insert

Those from RDG are total rubbish and made from cow dung, straw and high tensile toenail clippings, the Allen screws cut better.

I like the TPUN series purely on cost, remember I do this as a living on repair work not production which can alter the outlook of tooling v costs.

The TPUN series gives you 3 edges, 6 on some inserts and because it's 60 degrees it can be used for turning, facing and boring so one box of inserts can be pressed into use on many popular tools and that in itself is a saving.

.

aboard_epsilon
02-18-2009, 08:06 PM
Cant be that marvelous if you need 500 of them!

all the best.markj

John Stevenson
02-18-2009, 08:14 PM
Read post #15

Two boxes of inserts go out with every 4 tools, none ever come back.

aboard_epsilon
02-18-2009, 08:23 PM
yeah... that's TPUN11 not 16.

you said you bought 500 a time ...i read it as you bought 500 tpun 16-at-a-time ....in your post at 12:41 ..I was answering to.

anyway ..will have to get a DRO before i comit myself to them ...

as for general use, you have to take a large cut as your last and finishing cut with them ...and dials cant be relied on to do that ..(well not on my machine to do that, especially since the dials are in imperial ..and i work in metric ...)



all the best.markj

John Stevenson
02-18-2009, 08:38 PM
Yes 500 TPUN 16 at a time.

Anyway look here.
http://www.mscjlindustrial.co.uk/CGI/INPDFF?PMCTLG=10

Page 14

1.05 each to anyone sold as singles so I'll leave you to guess what you pay for a shed load.

.

motorworks
02-18-2009, 09:17 PM
John
Any chance of u posting a pic of the tools u make?
Have u used these for threading?
I made a threading tool that uses Tnmg inserts and it work well
for 8 tpi pipe. Use the -331 with a 1/64 radius.
eddie

Deja Vu
02-21-2009, 12:03 PM
Is it possible to provide a picture of the shaft welding partially turned off?....just to get an idea of the progression...

Thanks

John Stevenson
02-21-2009, 02:36 PM
Will do next time.
Got a large rotor in at the moment with a 50mm shaft and it's bent.
Trying to straighten one of these is so time consuming to get exactly right that I never bother now, I turn down undersize to get the bend out running off a good diameter and build up with weld and remachine.
At least this way you get it knob on first time.

Problem with this rotor is they need permission before going ahead whether to repair this motor or supply a new one so it's on hold.
.