Hole in Gear

This topic has 26 replies, 11 voices, and was last updated 10 December 2014 at 22:13 by Howard Lewis.

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30 November 2014 at 19:09 #23605
Neil Wyatt
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@neilwyatt
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30 November 2014 at 19:09 #171114
Neil Wyatt
Moderator
@neilwyatt
If you have a gear without a boss, but keyed to its shaft, and that needs to be securely located so it doesn't slide along the shaft, is it acceptable to drill a hole for a fixing screw between two of the gear teeth? It will remove about 50% of the bearing surface on the two tooth faces the hole will go between.

Neil
30 November 2014 at 19:15 #171115
Tony Pratt 1
Participant
@tonypratt1
Yes, or Loctite.

Tony
30 November 2014 at 19:50 #171118
Michael Gilligan
Participant
@michaelgilligan61133
Given the Mega Adept context … Loctite is not really practical

I wonder if a Wood's Metal plug would help ? … screwed in after the grubscrew and then filed to shape. … If you ever need to remove the plug, just heat to about 70 deg.C

MichaelG.
30 November 2014 at 19:55 #171120
Bodgit Fixit and Run
Participant
@bodgitfixitandrun
As long as it's central to the gear then it shouldn't be a problem. Seen many gears done this way. Mainly in the printing industry and with bacolite type gears. What is the width across the gear?
30 November 2014 at 20:10 #171121
Neil Wyatt
Moderator
@neilwyatt
Indeed, Loctite would prevent me getting it apart again.

Gear is 1./4" wide, 4BA will require a hole about 0.150" diameter.

Could go down to 6BA to avoid damage to avoid affecting the adjacent tooth space.

Neil
30 November 2014 at 20:15 #171122
Bazyle
Participant
@bazyle
Something using a circlip? If the key is constrained a groove in that and a recess in the gear above it.
Or an axial hole above the key such that it and the edge of the key can be tapped simultaneously.
Or a cheesehead screw with its head in a groove in the key. I was trying to think where I had seen this then remembered ti is the way tapered gibs are adjusted.

Edited By Bazyle on 30/11/2014 20:18:05
30 November 2014 at 20:55 #171127
Ian P
Participant
@ianp
Posted by Neil Wyatt on 30/11/2014 19:09:25:

If you have a gear without a boss, but keyed to its shaft, and that needs to be securely located so it doesn't slide along the shaft, is it acceptable to drill a hole for a fixing screw between two of the gear teeth? It will remove about 50% of the bearing surface on the two tooth faces the hole will go between.

Neil

If you have some exposed shaft either side of the gear you could fit two collars trapping the gear and its key. Maybe not collars but just spacers filling the gaps on the shaft.

Instead of having a grubscrew in the gear, what about putting the grubscrew in the shaft!

If the gear is close to the end of the shaft you could drill and tap the shaft axially as far as where the gear is located. Cross drill the shaft to take two small ball bearings and have a pointed grubscrew to push them radially outwards. That will fix it!

I dont know the diameter of your shaft but if its not smaller than 10mm it should be easy.

Ian P
30 November 2014 at 21:18 #171131
Michael Gilligan
Participant
@michaelgilligan61133
For those who haven't sussed the Mega Adept connection

See Neil's anguished cry, and the various pictures, on this thread.

MichaelG.
30 November 2014 at 21:28 #171136
Ian P
Participant
@ianp
Posted by Michael Gilligan on 30/11/2014 21:18:15:

For those who haven't sussed the Mega Adept connection

See Neil's anguished cry, and the various pictures, on this thread.

MichaelG.

Neil did not say which of the four gears he needed to secure to the shaft. My suggested method would be tricky on the mandrel but should work on the eccentric layshaft.

Ian P
30 November 2014 at 21:32 #171137
Michael Gilligan
Participant
@michaelgilligan61133
Ian,

Sorry to disagree; but this seems quite explicit:

[quote]

AAAAAARGH!

I left just enough space between the front and rear bearings for bull wheel, pulley and gear cluster, two adjusting rings, thrust race and thrust washer.

So how do I fit the key for the Bull wheel….?

[/quote]

MichaelG.
30 November 2014 at 21:58 #171140
Ian P
Participant
@ianp
Michael

My reply to Neil was a suggestion based on his actual question in this thread and I think a perfectly valid one.

He already has a thread on the Adept which I have dipped in and out of. If we have to read the all a members previous posts before composing a reply, it would all get a bit silly.

Even if I answered in the context of the Adept build my method would still be valid for the layshaft so there was 50% chance I got it right.

Ian P
30 November 2014 at 22:01 #171141
speelwerk
Participant
@speelwerk
Do not know if it is useable, but something like this is more elegant than drilling holes. Niko.

http://www.maedler.nl/product/1643/1621/spannsaetze-tt-bohrung-5-16-mm
30 November 2014 at 22:11 #171142
Michael Gilligan
Participant
@michaelgilligan61133
Truce, Ian

MichaelG.
30 November 2014 at 22:17 #171144
Keith Long
Participant
@keithlong89920
Neil if you can get at the side face of the gear when it's installed then you could mill a pocket in the side and drill down from that to the gear bore at an angle, so that the hole emerges pretty much at the centre line of the gear. Tap the hole for a suitable socket head grub screw. You should then be able to nip the grub screw up when everything is in place and secure the gear. If you did a "dry" assembly run first to get the position on the shaft that the grub screw contacts then you'd also be able to put a dimple on he shaft to get an even more secure fixing, as well as reducing the risk of getting burrs raised that might make future dis-assembly more difficult or possibly scoring the bearings.

This way you leave the gear teeth intact and the screw hole would have negligible effect on the gear strength

Edited By Keith Long on 30/11/2014 22:19:39
1 December 2014 at 07:05 #171157
Tony Pratt 1
Participant
@tonypratt1
Posted by Michael Gilligan on 30/11/2014 19:50:12:

Given the Mega Adept context … Loctite is not really practical

I wonder if a Wood's Metal plug would help ? … screwed in after the grubscrew and then filed to shape. … If you ever need to remove the plug, just heat to about 70 deg.C

MichaelG.

I also answered the OP's question as it was stated.

Tony
1 December 2014 at 07:09 #171159
Michael Gilligan
Participant
@michaelgilligan61133
No offence intended, Chaps !!

I was just trying to focus the discussion.

MichaelG.
1 December 2014 at 07:35 #171161
Ian P
Participant
@ianp
No offence taken.

Neil started it so its his fault anyway

Ian P

Edited By Ian Phillips on 01/12/2014 07:35:34
1 December 2014 at 07:37 #171163
Michael Gilligan
Participant
@michaelgilligan61133
, Ian

MichaelG.
1 December 2014 at 09:27 #171166
OuBallie
Participant
@ouballie
Posted by Neil Wyatt on 30/11/2014 20:10:22:

Indeed, Loctite would prevent me getting it apart again.

. . . .

Neil,

I'm surprised at that statement, and that you've got away with it.

Geoff – Waiting in anticipation
1 December 2014 at 10:36 #171176
Michael Gilligan
Participant
@michaelgilligan61133
Posted by OuBallie on 01/12/2014 09:27:18:

I'm surprised at that statement, and that you've got away with it.

.

Geoff,

I'm surprised by your surprise …

The breakdown temperature for most grades of Loctite is around 180 deg C

Neil's lovely blue paint job [and all the body-filler] would suffer greatly.

MichaelG.
1 December 2014 at 10:50 #171182
Neil Wyatt
Moderator
@neilwyatt
Thanks all,

I was getting little response in the Adept thread- it's of less general interest, and I thought I'd try for a wider audience, and certainly got a diversity of ideas!

As it 'appens i came up with an idea last night, and the same idea was posted on the adept thread.

I will replace the two adjusting rings with a single split ring that is retro-fitted around the spindle, set and locked in place.b Naturally this means using an extra thrust washer (as I don't want bearings running over the split), but it should be OK.

This also means I can make the new spacer exactly on size (less allowance for rotation) of the gap between pulley bush and thrust bearing.

Neil – listening to Marillion on the radio – and enjoying it!
1 December 2014 at 10:52 #171183
Gordon W
Participant
@gordonw
If I have understood this properly, then I would go with Bazyl's idea of using a circlip. Round wire clip with groove inside the bore and notch in the key. Work out the clearances and the wheel should knock off easily when needed.
1 December 2014 at 11:55 #171197
Bazyle
Participant
@bazyle
It's fun to have little problems like this to think about, even if you have now decided on a solution.
1 December 2014 at 12:01 #171198
OuBallie
Participant
@ouballie
MichaelG,

Agree about the heat, but on occasion that may well be the only, easy, solution.

Concentrate heat on the gear using a fine flame, with protection for the paint?

Cannot see Neil mangling the machine in use, and needing to dismantle it to make repairs.

Half the day gone, and I still need to do the spaghetti bolognese.

Geoff – Workshop time looks limited today
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