Thursday, January 13, 2011

Monty Remon's Taig Lathe Mods, Part 2

“I have 2 different copying systems for thread cutting plus a dedicated(?) threading system under developement, and have actually only cut 5 threads in anger!!!! The first was very simple copying system, consisting of 1/4" alloy bracket mounted on the carriage just clear of the x slide. A pivoting 1/2" square brass block tapped with 2 different target threads was mounted at the top, a sample of the target thread in rod form was screwed to the work piece, this attachment point was machined away after the thread was cut. I found a similar system on your site but it used a flexi plate or a bendy rod mounted on the x slide? Not wanting stacks of gears, shafts, levers and lead screws I did more research. I got confused by the Knaell systems, but liked the Keith Brooke copying method, I could understand that and had visions of slowly producing parts over weeks, so I made a start on the plate that fitted to the front of the carriage and then stopped! Time for a coffee, I then gave the whole lathe a severe looking at for half an hour and decided I was straying from the strait and narrow (PUN?)! I laid two lengths of 1/4" diam.,rod on the bed poking through the space in the headstock the Taig designers thoughtfully placed there for me, and measured a clearance of 4" diameter, enough to chuck 3.3" diam., work. A simple arrangement was arrived at to get from the clamp able mounting block made from 1"x1" scrap box alloy, through the guide assy.,(two 1"x1/4" scrap brass) clamped to the headstock and on to the carriage mounted plate. A piece of 1/2"x1/2" alloy is bolted on a vertical face of the clamp block and used to mount the thread magazine. The magazine is an off cut of 1 5/8" diam x 1/2" delrin with the target threads drilled and tapped at 45deg., stations. My scrap box is taking a beating. It's all been too easy so far, a bit of drilling, reamer work and tapping, sawing and threading and milling if you want to. Knowing that two 1/4 rods side by side are not as stiff as one 3/8" I elected to forget the drill chuck for target thread holding and try to get within 2" of the pulley assy., to reduce the bending forces. I made several dedicated male thread followers that clamp a through the spindle rod in place via the collet taper. The tpi range I selected are 18,20,22,24,26,28,32, & 40. The system worked well, a definite smug factor when I produced my first engine crank case back plate. A couple of points to note, the two guide plates are mirror image, the hole location was worked out to give 1/32" over the lathe bed and the same side clearance. The guide plates were machined as one and then used to machine the holes in the clamping block and the connecting plate for accuracy. When setting up the guide block assembly fit the clamping block to the l.h. end of the rods and position the carriage near to the headstock, tighten things up, now any alignment errors can only decrease and the system should not bind. The guide assy., can be left clamped in place, the carriage plate bolts were slackened off a flat, the rods finger tightened and then the plate locked? Not counting the bolts this gadget can be made with 10 simple parts and two of those are rods.”


“Now the other system, my Thread Box. It has not been a labour of love, more a pain in the backside, too much coffee and head aches over a six month period, but I'm at the MK 2 version. It is the mounting system that I've yet to sort out. Basically it is just a box (HA!)that is bolted to the head stock and the output rod connected to the carriage. The input shaft is driven by a gear or toothed belt mounted on the end of the pulley. The drive of 2:1 ratio can be swapped round to 1:2 ratio, this gives two ranges but infinitely variable pitch selection within each range, at the moment this version has a 5 to 80 TPI range (5-20+ 20-80), a design change could make this 10 to 160 easily. To cut a thread just dial it in, the settings are obtained from a chart, METRIC? B.A? A.N.F? CLINGON? M.E.. NO PROBLEM, I YOU CAN SPELL IT YOU CAN CUT IT. The down side- you can't cut rod lengths but a cut of 1/2" to 1" depending on the range selected is ok.”


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