We're entering the final stages of making the Myford internal grinder now. The few remaining parts needed have arrived from China. Toothed belt and toothed pulleys. The grinding wheels as I think I've suggested in a previous blog from Good Old Blighty.
Only job remaining now is to bolt the motor carrying bracket to the back of the cross slide. The belt tension will be adjusted on the compound slide if its set in line with the motor shaft. I'm thinking that I can get away with a few more microns back and forth of the compound slide to actually grind the gear to finished size without over stressing the belt.. Micro adjusting the cross slide will not be a good idea without a D.R.O. (which I have, but it's still boxed awaiting fitting. This digital upgrade is booked in for when the lathe is moved into 'The New Sidevalve Bar'....hum!... when it's built)
Just as the above tooling was in the 'Final Work In Process Stage'. I happened to have to make a visit to a local Wire Eroding Company. I was collecting bespoke engineered parts for one of the machines in the Government workshop. I seem to have a habit of being invited onto factory floors and this day I was on another new one....How lucky am I. H &S can sometimes thwart this wonderful experience. Must be the way I dress?. or look? In front of me as I collected our small order (in comparison) were 2 x huge gears that according to the owner weighed in at least a tonne a piece. A fork truck had to lift them on the eroding bed. Got to have been at least 0.75mtr x 0.75mtr in size. Down the centre ran a hole for shaft fitting but more importantly they had keyway slots...HOLY MOLY!!!!!!!!!!!!! "Did you cut those keyway slot?" "Yes, we erode to tolerances of +/- 2 microns"....(Dude, that's 0.002mm.) Alb's brain all of a sudden thinking that's way better tolerance than a 1928 Raleigh needs. "Send me your DXF files and I'll give you a price" "Awesome I will"
So, through Government contacts I had drawn for me 2 x DXF & PDF files at a design studio. (2 of the gears are the same shaft dimension) It's not only what you know but who you know.... A lifetime building and enjoying camaraderie with people who understand dirt under finger nails and can talk the same language has it's rewards. The cost was nil. Free to me !!!! Much appreciated.
I emailed the files to 2 Wire Eroding Companies on our Government supplier list. Competitive quote hunting as you do as I'd no idea what cost to expect.... By return I received a quote for 3 x gear blank centres eroded to match the 2 x files. Local too, only 4 x miles away, so I can do a collect and not risk postal loss. In todays money I thought the price was good and of course it was going to speed up the Raleigh gearbox rebuild by months or even years.......I'd no idea how long it would have taken to work the gear blanks on the lathe and then after grinding perfect the art of broaching keyway slots....A skill I'd like to have but I'll have to save learning it for later, when I'm older.
That's how a sharp change of direction happened, all the internal grinder fabrication and parts now stored in a box for safe keeping, they'll come in handy one day I'm sure. Hours not totally wasted as far as I'm concerned.
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