05-09-2015, 06:04 PM
I wondered the same thing Ken, would be worried it could back off to easy.
Free advice is worth exactly what you payed for it.
Greg
Greg
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Kondia FV-1 Head disassembly
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05-09-2015, 09:08 PM
Thanks guys!
Tom - the thread was cut on my friends 10x20 lathe, which doesn't have a thread dial on it, so I kept the half nuts engaged and reversed the motor at the completion of each pass. Ken - in checking my tooling, I currently have three holders with M12x1.75 (ER32 collet chuck, boring head and MT3 adapter) and three that are 1/2-13 (drill chuck, shoulder mill and face mill). It turned out that the 1/2-12 tooling was just the homemade stuff that came with the mill (I won't be using any of that). As you can see, they are colour coded and the two shallow grooves you see on the drawbar will be filled with the corresponding colour, so (in theory) I shouldn't mix them up... So I screwed using a thrust bearing I take it? Thrust washers here look the same, although they have rollers instead of balls and I wasn't able to get one with the dimensions I wanted. The Kondia drawing shows something between the drawbar and the top of the spindle drive shaft but doesn't list what it is. I'll mill the hex on this one and then I can heat it up and separate the two parts (I used loctite as I needed the mill to drill and pin it).
Hunting American dentists since 2015.
05-09-2015, 09:56 PM
Not saying it won't work Darren, maybe they're common, just not something I'd have expected.
Free advice is worth exactly what you payed for it.
Greg
05-09-2015, 10:52 PM
Thanks Greg - I understood where you were coming from. I'm doing some more searching to see what I can find...
Hunting American dentists since 2015.
05-10-2015, 06:14 AM
(05-09-2015, 09:08 PM)Mayhem Wrote: So I screwed using a thrust bearing I take it? Nope, it is a good idea.  A plain washer does two main and a third things: 1, It distributes the load evenly. 2, The nut/bolt head acts on a flat surface allowing the force to be directed to the thread with lower frictional loses between the nut/bolt head and the surface component. (stops it coming undone) And 3 stops damage to the nut/bolt head or the surface of the components. A thread works like a wedge, two wedges being forced together it is this friction between the two wedges that holds the thread together and stops it coming undone. Frictional loses between a rough(ish) surface and the nut/bolt head can amount to 50% of the torque applied - so just when you thought it was tight - it ain't  my 2 cents   DaveH
05-10-2015, 06:50 AM
Thanks Dave - once I have finished one I'll be able to report back on how it works. My concern is that it may come undone, given the previous comments/queries. I had the drawbar come loose the other day whilst making a cut and it wasn't fun.
Today I tried to mill the flats and I need to check the tram (which I thought I got correct), or the part flexed, despite my machine jack. I am still above the final 19mm dimensions but the hex is tapered. It measures 19.1 at the top and 19.5 at the bottom. I forgot to take a close up pic of the finish but will do later. I was very happy with it. .050" cut at 950 rmp
Hunting American dentists since 2015.
05-10-2015, 06:56 AM
Darren, I'm kinda late on this reply (it takes a while to get the internet up here in Canada
 ) but I thought the same thing the others did, even before I read their posts (honest, I did).Now the real reason for my post, is there any chance of a pic of your "dirty" lathe today? Just to prove that it's still "dirty"  Steve
Busy Bee 12-36 lathe, Busy Bee Mill drill, Busy Bee 4x6 bandsaw, Homemade 9x17 bandsaw, Ad infinitum.
05-10-2015, 07:17 AM
Sorry Steve - the lathe is at my other shop, which is about 15 miles form here. But other than cleaning most of the swarf off of it, it is still dirty. I usually give it a wipe down and an oil prior to using it. Don't be confused by the rebuild pictures, she is not a show car...
Hunting American dentists since 2015.
05-10-2015, 08:17 AM
I do see one other reason why I like a 5C collet block: The collet "nose" isn't larger than the block.
This feature allows the collet block and workpiece to be held in the middle of the vise jaws where the force won't shift the movable jaw to one side or the other. The ER style has a nut much larger than the collets so you can't as easily get it in the middle of the jaws. A parallel spacer on either side of the hex/square of the block solves that. The cutter in use is perfect for the application, and looks vaguely familiar. 
05-10-2015, 08:26 AM
(05-10-2015, 06:50 AM)Mayhem Wrote: My concern is that it may come undone, given the previous comments/queries.I won't come undone provided it is tightened correctly (normal force). To rely on the fictional force between the nut/bolt head and the component to stop the thread coming undone is not the correct way to tighten a thread. Hex milling - have you tried a smaller cut say .005" to .010" to see if the dimensional difference decreases. DaveH |
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