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Tim Leech - 12 Dec 2006 17:47 GMT

At long last, here's an arbor I made for cutting gears on my Mikron.
It's just a length of silver steel the same dia as the bore of the
gears I was making. In this case I have a collet of the same diameter
so it was easy.
At the RH end is a separate collar to give a shoulder to clamp the
gear(s) against. It's loctited onto the shaft, I did put a light knurl
onto the shaft at that point to help make it more secure on the
otherwise smooth finish. Of course if you prefer to whittle it out of
solid with your penknife, that's your choice.
The LH end has a centre hole for the hobber tailstock, and a thread
for the clamping nut. The collar in the middle is just a loose packing
piece.
I skimmed the face of the fixed collar after the loctite had set, just
to make sure it was square to the shaft.
Length of this one is about 5", anything from about 3" to 6" should be
OK.
Don't worry about the tooth marks, I was cutting some small gears on
it.

http://web.onetel.com/~duttondock/Pictures/geararbor-1.jpg

HTH

Tim
Dutton Dry-Dock
Traditional & Modern canal craft repairs
Vintage diesel engine service

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Mark Rand - 12 Dec 2006 21:37 GMT

>At long last, here's an arbor I made for cutting gears on my Mikron.
>It's just a length of silver steel the same dia as the bore of the
[quoted text clipped - 23 lines]
>Traditional & Modern canal craft repairs
>Vintage diesel engine service

Thanks for that.

I'll just nip out and turn a bit of extra length onto the 2 1/4" arbours I was
using to turn the gear blanks. Now where did I leave that putting-on tool? :-)

More specifically, I've been working on the assumption of a 1/2" arbour at the
drive end and whatever fits for the other end, with centres at both ends,
because they have been turned between centres anyway.

I've not been bothering with threading them, since I've been holding the gear
blanks on the arbours with Loctite 603.

These are the sort of thing I've got now:-
http://www.test-net.com/arbours

The top picture shows a couple of arbours, one that has been used to turn the
blank down to size on. They are too short.

The Middle picture shows one of the slightly awkward gears, The shaft is 1/2"
diameter, so that's good, but the total length is just shy of 4 1/2" and will
want a bit extra for clearance from the tailstock. I'll extend it beyond the
gear to a total length of 6"

The bottom photo is the awkward one. The shaft to the left of the pinion is
1/2" and 45 thou smaller than the tooth root diameter, that's ok. The shaft to
the right of the pinion is 17 thou _larger_ than the tooth root diameter and
is also a needle roller bearing surface. I think that I need to make something
like the picture below the photo, again for a total length of 6"

Regards

Mark Rand
RTFM

If I were doing this for a living, I wouldn't even make enough to starve on,
but If I were doing it for a living I might not enjoy it so much.

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Tim Leech - 12 Dec 2006 22:11 GMT

>>At long last, here's an arbor I made for cutting gears on my Mikron.
>>It's just a length of silver steel the same dia as the bore of the
[quoted text clipped - 46 lines]
>want a bit extra for clearance from the tailstock. I'll extend it beyond the
>gear to a total length of 6"

Let me give it a bit of thought tomorrow and check measurements on the
machine, you might not need to make too much use of that expensive
putting-on tool.
I'll get back to you.

>The bottom photo is the awkward one. The shaft to the left of the pinion is
>1/2" and 45 thou smaller than the tooth root diameter, that's ok. The shaft to
>the right of the pinion is 17 thou _larger_ than the tooth root diameter and
>is also a needle roller bearing surface. I think that I need to make something
>like the picture below the photo, again for a total length of 6"

Tim
Dutton Dry-Dock
Traditional & Modern canal craft repairs
Vintage diesel engine service

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Mark Rand - 13 Dec 2006 01:07 GMT

>Let me give it a bit of thought tomorrow and check measurements on the
>machine, you might not need to make too much use of that expensive
>putting-on tool.
>I'll get back to you.

Don't worry about that, I'm having fun and have just about got the hang of
making the things to the desired tolerance.

PS

If anyone wants to see why the gears need replacing, clicking on the lower two
photos and suffering the full size pictures shows the reason.

No progress tonight because I had to go back into work, and tomorrow night is
the office Christmas party (I'm organising it, £450 bill and an indeterminate
wait for expenses) If I'm sober on Thursday, I've got a day off to play in :-)

Mark Rand
RTFM

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Tim Leech - 13 Dec 2006 08:27 GMT

>These are the sort of thing I've got now:-
>http://www.test-net.com/arbours
[quoted text clipped - 12 lines]
>is also a needle roller bearing surface. I think that I need to make something
>like the picture below the photo, again for a total length of 6"

Do the needles actually run on the shaft? or does the bearing have a
proper inner race? If the latter, a few 'tooth marks' where the hob
runs off won't matter greatly.
How long is the leadscrew? I'll have to check, but I think the 1/2"
shaft could be 'lost' down the drawtube.
Alternatively, is the bearing surface bigger dia than the leadscrew, &
what dia is the leadscrew? Might there be mileage in shrinking a
sleeve on for the bearing, if the dia is bigger than the screw?

Cheers
Tim
Dutton Dry-Dock
Traditional & Modern canal craft repairs
Vintage diesel engine service

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Tim Leech - 14 Dec 2006 08:52 GMT

>I'll just nip out and turn a bit of extra length onto the 2 1/4" arbours I was
>using to turn the gear blanks. Now where did I leave that putting-on tool? :-)
[quoted text clipped - 11 lines]
>The top picture shows a couple of arbours, one that has been used to turn the
>blank down to size on. They are too short.

The larger dia. one should be OK if it can be reversed, ie the longer
shaft at the collet end. Is it 1/2" that end? Similarly for the
smaller gear, if the longer end can be held in a collet it should be
OK.

>The Middle picture shows one of the slightly awkward gears, The shaft is 1/2"
>diameter, so that's good, but the total length is just shy of 4 1/2" and will
>want a bit extra for clearance from the tailstock. I'll extend it beyond the
>gear to a total length of 6"

*If* the shaft can pass into the drawtube, and it's centred at the
gear end, that should be doable.

I'll make a point of checking later this morning. Off to the dentist
now :-(

How's the hangover ?<G>

Cheers
Tim

Dutton Dry-Dock
Traditional & Modern canal craft repairs
Vintage diesel engine service

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Mark Rand - 14 Dec 2006 21:42 GMT

>>I'll just nip out and turn a bit of extra length onto the 2 1/4" arbours I was
>>using to turn the gear blanks. Now where did I leave that putting-on tool? :-)
[quoted text clipped - 16 lines]
>smaller gear, if the longer end can be held in a collet it should be
>OK.

Actually, the smaller one isn't a gear, it's an arbour that hasn't got a gear
on it yet...

>>The Middle picture shows one of the slightly awkward gears, The shaft is 1/2"
>>diameter, so that's good, but the total length is just shy of 4 1/2" and will
[quoted text clipped - 3 lines]
>*If* the shaft can pass into the drawtube, and it's centred at the
>gear end, that should be doable.

All the arbours are ending up with centres on them at both ends because they
are being turned between centres!

>I'll make a point of checking later this morning. Off to the dentist
>now :-(
>
>How's the hangover ?<G>

It took a while to get going this mor^H^H^Hafternoon :-)

>Cheers
>Tim

Mark Rand
RTFM

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Tim Leech - 14 Dec 2006 11:24 GMT

>I'll just nip out and turn a bit of extra length onto the 2 1/4" arbours I was
>using to turn the gear blanks. Now where did I leave that putting-on tool? :-)
[quoted text clipped - 22 lines]
>is also a needle roller bearing surface. I think that I need to make something
>like the picture below the photo, again for a total length of 6"

I've now checked, a W20 collet will pass 9/16" through, and the
drawtube looks to be made to match. It's stuck in a corner at the
moment, so I haven't physically tried but can't see any reason why it
shouldn't.
For what I assume is your cross feed screw, it probably wouldn't be
essential to have tailstock support as it's a small gear which could
be mounted pretty close to the collet chuck. Otherwise it's probably
not a massive job to take the centre out of the tailstock and make a
little bush to stop the screw floating about.

Cheers
Tim

Dutton Dry-Dock
Traditional & Modern canal craft repairs
Vintage diesel engine service

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Mark Rand - 14 Dec 2006 22:24 GMT

>I've now checked, a W20 collet will pass 9/16" through, and the
>drawtube looks to be made to match. It's stuck in a corner at the
[quoted text clipped - 8 lines]
>Cheers
>Tim

Because the cross feed screw pinion and bearing journal are going to be a
bugger to harden without turning the whole thing into a corkscrew, I've
re-thought the way I'm doing that one. I'm going to use a bearing with an
inner ring and use a 1" long inner ring as a coupler between the pinion shaft
and the screw shaft. So the pinion will have a 3/8" stub shaft at the end
rather than the 9/16" it's got at the moment. The original pinion must have
been cut on a gear shaper in order to avoid messing up the 9/16" journal
that's next to it.

That means that I'll have to bore the hole in the saddle out from 3/4" to
13/16", but that's manageable.

Mark Rand
RTFM

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Model Forum / General / Models / December 2006

For Mark Rand - More gear-related stuff