cutting 20tpi on clarke cl430

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cutting 20tpi on clarke cl430

This topic has 15 replies, 4 voices, and was last updated 3 September 2015 at 11:06 by mick70.

Viewing 16 posts - 1 through 16 (of 16 total)

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2 September 2015 at 15:50 #15803
mick70
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@mick70
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2 September 2015 at 15:50 #202968
mick70
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@mick70
as anyone cut above thread?

listing in manual starts at 22 tpi up to 40.

thanks
2 September 2015 at 15:54 #202969
mick70
Participant
@mick70
don't worry had another look and it's numpty operating lathe that read it wrong.
2 September 2015 at 17:51 #202975
Bazyle
Participant
@bazyle
In general when you have this sort of thing look for a thread you do have the settings for that is a simple multiple like 2:1 or 3:2 as you can probably modify part of the gear train to provide the ratio.
2 September 2015 at 18:09 #202978
mick70
Participant
@mick70
Set it up per manual and comes out really coarse thread.

Going to have another look tomorrow as might end up using hammer on it.

t
2 September 2015 at 18:18 #202979
Keith Long
Participant
@keithlong89920
Try looking in the second column of the changewheel / tpi chart, bottom row, with the speed selector lever set to position 2 ie handle to north east.
2 September 2015 at 18:25 #202980
mick70
Participant
@mick70
I did.

Even stripped them all of to double check I had put right gears in.

Got it running on its slowest speed as well.
2 September 2015 at 21:28 #202986
Bazyle
Participant
@bazyle
The chart in the manual is looking a" bit crap".

It gives, for 20 tpi 50/36 56/27 that speeds up the leadscrew so cuts a coarser thread than the leadscrew.

What is the leadscrew pitch?
2 September 2015 at 23:54 #202996
Michael Gilligan
Participant
@michaelgilligan61133
Posted by Bazyle on 02/09/2015 21:28:52:

It gives, for 20 tpi 50/36 56/27 …

.

Bazyle,

Did you spot Fig.21 on the next page of the manual ?

It shows a reduction before gear 'A' … so that's not the full train.

MichaelG.

.

Edit: I just found the Parts List … which may be useful

Edited By Michael Gilligan on 03/09/2015 00:01:02
3 September 2015 at 00:17 #202997
Bazyle
Participant
@bazyle
AH, well spotted but it is the pair behind A in permanent position that are the extras, and look to be 2:1. It must have a metric leadscrew as the metric .table aligns quite well, but not accurately to a 3mm pitch.
3 September 2015 at 02:06 #202999
Bazyle
Participant
@bazyle
You struck unlucky with choosing 20tpi. The relative ratios of all other threads, metric or imperial are correct one to another, except for the 20 tpi setting. It is over 30% off. Not sure if the starting position is quite right still as I think that fixed pair I mentioned above need to be 16/35 (or 32/70 ) with a 1.5mm leadscrew, ie not quite 2:1.
3 September 2015 at 06:19 #203000
mick70
Participant
@mick70
cheers for replies.

be glad when i get full set of gears for southbend.
3 September 2015 at 07:17 #203004
Michael Gilligan
Participant
@michaelgilligan61133
Exploded View in the parts list appears to show both a double gear and a triple … this could get complicated.

Probably worth turning the headstock spindle by hand, and counting turns of gear 'A' to establish a baseline.

MichaelG.
3 September 2015 at 07:24 #203006
mick70
Participant
@mick70
right just been out to reset it for normal turning.

had a look at chart on inside of cover and it gave a totally different set of gears.

gave it a go and worked great.

gears it listed were

a=50

b=36

c=56

d=42
3 September 2015 at 08:30 #203008
Michael Gilligan
Participant
@michaelgilligan61133
Excellent Result !!
3 September 2015 at 11:06 #203027
mick70
Participant
@mick70
sent clarke e-mail explaining.

they say they will look into it and if required update manual to match.
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