Chester Crusader screw cutting ratios

[jimmy bParticipant @jimmyb]

Related to my earlier post.

I may need to cut 0,35 pitch thread, the threading charts only go down to 0,4 pitch. I don't know what size any of the gears are, so I've come to a full stop!

Does any one know the number of teeth on the Crusader gearbox?

Thanks again!

Jim

[jimmy bParticipant @jimmyb]

[HopperParticipant @hopper]

Can you set the gearbox to .70 pitch and then double the ratio of the gears between the headstock spindle and the gearbox input shaft to get .35?

[Howard LewisParticipant @howardlewis46836]

For my BL12-24 (BH600, Chester craftsman looka like) I made a 80T gear gear to replace the 40T on the input tom the Norton box. If you can make do the same thing with your Crusader, as Muzzer says, set up for twice the required pitch, and you are away.

Do you have any alternaive gears for the Norton box inmput?

(My BL 12-24 came with 32T and 36T alternatives to extend the range of possible threads, do you have any similar alternatives)?

Howard

[larry PhelanParticipant @larryphelan54019]

I had to do something similar with my Craftsman lathe in order to cut an M12 thread.I just had to change the ratios and it worked out fine.Some lathes can cut more threads than listed on the charts,so it,s worth playing around.

[richardandtracyParticipant @richardandtracy]

I don't know if the program I wrote for a Clarke 500 type lathe could be adapted for you. Take a look at this thread:

http://www.model-engineer.co.uk/forums/postings.asp?th=130270 [sorry, my tablet can't cope with the forum's code to make it a live link]

It may suggest some different wheel combinations for you.

Regards

Richard

[jimmy bParticipant @jimmyb]

Thank you all for the input.
I’m stumped now. Checking by turning the chuck 10 times, I can’t get finer than 0,4 pitch.

I’ve ordered a die now, as I doubt I’ll have to do a thread that fine again…

Jim

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