# Modding my threading drop in dial



## Blogwitch (Feb 5, 2015)

Just a little history to tell you why I did this mod.
On larger metric machines, as you go from one range of pitch threads to another, you have to remove the drop in dial and replace the gear on the end of the spindle, to allow the gear system to stay synchronised with the large leadscrew.

My machine is a Chester Crusader, the same as a lot of other machines you can buy, and it uses three gears, just like the one below, with 14, 15 and 16 teeth. It would be a real PITA to keep changing these gears, so I modified my block to like others I had seen, which had a ganged gear set








The first job was to get rid of the loose bolt that went thru the block, had a spacer fitted and then screwed into the side of the saddle. I made a standout with a built in spacer.
If you notice, the leadscrew guard has been removed, that was because it cramped my overall saddle travel a little, and I don't know if this mod would still work with the guard in place.







The main part of the job was to skim the two larger gears to half their width. This was to allow the gears to be fitted together, but still allow one gear to mesh with the leadscrew without it fouling the other gears.







The next job was to make two more holes in the main block at 12.5mm pitch between centres.







A spin handle was made up to match the rest of the handles on the machine, straight sides dropping down to a taper.







This is shown set up for the 15 tooth gear. Notice how the 16 tooth now clears the leadscrew.






This one shows the 16 tooth in synch with the leadscrew. It takes only seconds to switch from one size to another, plus I won't have to go searching around to find where I had put the spare gears.






Job done

John


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## mcostello (Feb 6, 2015)

great idea.


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