Our lathes differ in relation the chain drive; with mine looking like it originally had a lay shaft (based upon the tumbler bracket and the length of the shaft for the gear cluster.
Chain sprocket on tumbler output
Here you can the vacant hole in the bottom LH corner of the bracket. The gear cluster, the feed bracket and the selector are visible as well
Note on his lathe, the tumbler gears are open (you can see this in the 4th and 5th pictures in the previous post.
Rather than mess around with a lay shaft, which meant another set of sprockets and chain, I decided it would be simpler to extend the cluster gear shaft to accommodate the chain sprocket and align it with the chain sprocket on the tumbler. To do this I needed to make up two brackets that would straddle the tumbler bracket and support the (new) longer drive shaft. I mocked these up using cardboard, then Perspex and finally I cut them from 3mm plate.
Perspex mock up
Top view (1" stud filling in as an extended shaft!)
Using such a large bolt seemed silly, so I turned a plug to accommodate a 3/8-16 bolt
A couple of bronze top hats and the 1 shaft is now supported and ready to have the gear cluster and chain sprocket fitted.
Final brackets finished and in position
As the shaft will now turn (in the original design the gear cluster rotated on the shaft), a bronze bush will be turned up and inserted into the housing in which it resides, along with a thrust bearing.
The other lathe has a 21t sprocket driving a 76t sprocket, giving it a drive ratio of 3.62:1. The sprocket I have on my tumbler has 15 teeth and the closest off the shelf sprocket I could find to match the aforementioned ratio has 54 teeth. This will give me a drive ration of 3.6:1, so I'm happy with that.
Chain sprocket on tumbler output
Here you can the vacant hole in the bottom LH corner of the bracket. The gear cluster, the feed bracket and the selector are visible as well
Note on his lathe, the tumbler gears are open (you can see this in the 4th and 5th pictures in the previous post.
Rather than mess around with a lay shaft, which meant another set of sprockets and chain, I decided it would be simpler to extend the cluster gear shaft to accommodate the chain sprocket and align it with the chain sprocket on the tumbler. To do this I needed to make up two brackets that would straddle the tumbler bracket and support the (new) longer drive shaft. I mocked these up using cardboard, then Perspex and finally I cut them from 3mm plate.
Perspex mock up
Top view (1" stud filling in as an extended shaft!)
Using such a large bolt seemed silly, so I turned a plug to accommodate a 3/8-16 bolt
A couple of bronze top hats and the 1 shaft is now supported and ready to have the gear cluster and chain sprocket fitted.
Final brackets finished and in position
As the shaft will now turn (in the original design the gear cluster rotated on the shaft), a bronze bush will be turned up and inserted into the housing in which it resides, along with a thrust bearing.
The other lathe has a 21t sprocket driving a 76t sprocket, giving it a drive ratio of 3.62:1. The sprocket I have on my tumbler has 15 teeth and the closest off the shelf sprocket I could find to match the aforementioned ratio has 54 teeth. This will give me a drive ration of 3.6:1, so I'm happy with that.
Hunting American dentists since 2015.