The last 2 weeks have been devoted to two topics:
- Getting the new mill into service &
- Completing phase 1 of the pump drive for Befur’s engine.
The New Mill
The new Rambaudi mill is living up to my expectations, it is a lovely machine. However, getting any new machine into harness can take some time. In this case we have been working on tooling (as I had to replace all the old R8 tooling with the Int40 standard for the new machine), building and fitting the Digital Read Out (DRO), and lastly repairing a broken tool-tray which was causing a coolant leak.
Tool post grinding with a Proxon/Dremel
The tooling change threw up an interesting problem – the Autolock chuck provided with the mill had two metric versions of one of the larger sizes of collet and was missing one collet. The the replacement for the missing one that I purchased on-line proved to not be the one advertised – the net was I had duplicated metric collets in two sizes.
The imperial versions are just a fraction larger in both cases. So, for example, the smallest collets are 6mm and 1/4 inch, but I had two 6mm ones 😦 . As I could not find any other sources of imperial collets I decided I needed to fix the problem. So (with nothing to lose) I fixed the “Dremel” to the tool holder on the lathe (with some zip clips!) then installed a small industrial diamond burr in the Dremel’s chuck, clocked-up the undersized collet in the 4-jaw chuck, and then used the lathe’s self-act and slowest speed to re-bore (re-grind really) the collet to size – and it worked!!! It worked so well that I then went on to apply the same treatment to the other duplicate metric collet – 30mins work and we were in great shape… So I can thoroughly recommend tool-post grinding!
The only damage to the mill as delivered proved to be one of the tool trays fixed to the end of the table. This had been cracked and distorted by some unknown force, and this caused a minor flood the first time I used the coolant, so needed to be fixed. Some thickened epoxy fixed the crack, and the mill was used to refinish the distorted face – thus healing itself! The video below serves to show how nicely and quietly this 1972 machine still runs!
The Pump Drive
As I think I have mentioned earlier, the Leak Compound engine we are fitting to Befur needs to run at up to about 600rpm to generate full power. But the reciprocating feed and vacuum pumps will be very unhappy running that fast. While at the same time the alternator we need to provide power for the boiler’s burners, navigation lights and radio will not work below 2,000rpm. So, we needed to provide some arrangements to provide slower and faster outputs from the engine.
I found that one can buy very neat pre-built worm (blue) gear boxes with ratios from 7.5:1 to 30:1 online, and this could be used to provide the slower speed for the pumps. Without needing to use huge pulleys to provide the alternator feed, a two-stage gear up seemed like the right answer.
So I drew up an assembly with duplex chain driving a counter-shaft driving the worm gear box and a large v-belt pulley which would in turn drive the alternator.
This proved a salutary experience, making me much less critical of errors in the drawings, as there were plenty in mine! However, a couple of weeks work provided a working “phase 1” assembly. Phase 2 is fitting the scotch cranks to drive the pumps. Here’s a video of it idling away (forgive the temporary long key and zip-clip extended v-belt!)