MattF
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Drummond M
Nope. Sliding backgears on that photo, & it's not a pre-B as the leadscrew is side mounted.
Drummond M
Nope. Sliding backgears on that photo, & it's not a pre-B as the leadscrew is side mounted.
And one of mine
Which other Drummond has the knock-off bar along the front?
...now have 6 to 1 ratio is this low enough...
Here is the screw cutting chart for a Drummond / Myford M.
I Just want to get the carriage feed working I dont want to do any screwcuttingWhat are you trying to achieve?
On my lathe, the power feeds go from 0.001" to 0.008" per revolution. That equates to screw cutting pitches of 1000 tpi to 125 tpi.
Assuming your leadscrew is 8 tpi, a 6-fold reduction on that would give 48 tpi, 2 1/2 times faster than the coarsest feed on my machine.
It might be good to look at the gearing set ups for Myford and Boxford lathes (as this information is easy to find and both machines should have the same leadscrew pitch as your own) and copy that as closely as you are able with the gears you have.
I was just about to point him to:
https://www.practicalmachinist.com/...nd-history/drummond-bros-3-1-2-m-type-312079/
where there is a photo of the same chart. Maybe there is something in that thread you have not seen before.
It is good to see Drummond's translation gear (46/73).
Middle right of the picture I posted are the fine feeds, marked 110 and 174 tpi.I Just want to get the carriage feed working I dont want to do any screwcutting
OK have simplified it some more still have 6 to 1 ratio
Thanks this is my first lathe so it is a suck it and see process but getting a lot of helpWhat we are saying, and what the chart is saying, is that 6 to 1 reduction is not enough. The ones on Drummond's own chart work out to be 13.75 to 1 and 21.75 to 1 so you will be feeding more than twice as fast as that.
HOWEVER, and this is where someone more familiar with the machine than I needs to chip in, your latest photo seems to show you taking the drive from the backgear. If that is possible, you might try combining the lower two gears from your picture in post 28 with the upper drive arrangement in post 34 and that will be a big improvement.
I found this when looking for the screwcutting chart, where the poster shows a similar set-up, with the feed gears driven off the backgear:
https://www.ukworkshop.co.uk/threads/drummond-b-lathe.126016/
Thanks this is my first lathe so it is a suck it and see process but getting a lot of help