Bridgeport Interact 4 Series 2 to Acorn6 build

[richardb15]

Not directly related to Centroid Acorn, but the milling machine was used to create the arbor for the valve seat cutting, which in turn will be done on the mill when I've got the castings to that point.

First job to dig through the wife's billet bin (that is a real thing, a big box of barstock offcuts, not a euphemism) for something about the right size, BT40 toolholder beside it for ref:



After turning a dia 30 on the lower end and boring/reaming a 3/8" hole it's onto the mill for the insert shoe features




After that a fit check of the shoe and carbide guide rod seem good so back into the CNC lathe the other way round to create the BT40 taper and M16 thread in the other end




After a bit of CAD and 3D printing I made the diameter setting tool ($167 to buy, less than $5 to make) so that is another bit ready to go, and another capability for the mill.


Once we've bored the holes, made and fitted the valve guides into the castings we can cut the seats, exciting stuff!

[richardb15]

The veteran Triumph barrel project hit a road block at the weekend.... after lots of setting up we machined the first inlet port thread, so an end mill to create the top surface and inner ID, chamfer tool to give a nice lead-in, and an M6x1 thread mill to cheat and do the M30x0.9mm pitch thread, after sneaking up on the finished diameter all was good:





From a batch of 12 castings I guess we got lucky, this one machined so nicely, the next one broke the end mill facing off the top, then I file tested the rest and all castings have a hard spot in the same place. I cooked one at 940degC for 1.5hrs then cooled over 16 hours, no bueno, still hard

Time to get more creative and sort out what I thought was a long term project, now top of the priority list

[richardb15]

The Bridgeport mill only has a 4000rpm spindle, we have a Planetor orbital jig grinding head but it would be nicer to have a high speed spindle on the mill for grinding jobs, like Triumph cylinder inlet ports..... Oh yes, a Centroid CNC ID, OD and thread grinding machine, nice. The Bridgeport has a screwed ring under the quill that holds the lower bearings in place. That would be a nice mounting place for a high speed spindle:



Someone in the past has removed that ring with a pin punch but 5 mins and a bit of scrap had a pin spanner that did the job very nicely:


Now we can thread that and make an adaptor to fit over, clear the existing spindle nose, and mount the high speed motor. A handy 140mm dia 4140 billet took one for the team, side one of the adaptor in the CNC lathe:



Side 2 done and into the wife's Elliot mill and rotary table for the holes, can't use the Bridgeport as we had the spindle bearing cap off!


On the left here is the Hauser high speed grinding spindle off our jig borer, the middle is the Bridgeport lower bearing screwed ring with 3 M6 holes added at the same PCD as the Hauser motor mount holes, and on the right the adaptor we made:


Dry assembly test on the bench:


The upper side, you can see the sintered air filter for the Hauser motor so it can breathe as it gets hot/cold:
*edit - realised after typing that the sintered filter is not for allowing the motor to breathe, its for a air supply to blow through the motor assembly to cool it!*


Here mounted on the Bridgeport:


Last job of the day, run off a batch of mandrels in different lengths and 8mm, 3/8" and 10mm fittings for grinding wheels. We need to make a nut for the Hauser motor too as it was missing when we got the machine. After that need to sort a power supply as the motors use a 3phase 110v supply which does not match anything we have, so I guess a 230v-110v 1ph transformer, then a 110v 1ph to 110v 3ph VFD will be the best option, then we can also change the motor speed if we want rather than stuck at 50Hz, which I think is around 20,000rpm for those motors.