collets for Centec 2 mill

All the draw bar sizes I've seen for the centec2 mill seem to 3/8's (.375" -9.525mm) mine is 5/16's (.3125"-7.9375mm) other than bore out my drawbar to 3/8's or 10mm I'm struggling to find collets of the 5/16 18tpi variety .

Anyone have any suggestions on the best way around this . 

Sean

Edited By sean logie on 25/07/2017 08:06:23

The vertical head is 3/8 and intended for collets or cutter holders

The horizontal is 5/16 and longer and is intended for retaining the horizontal arbor only.

If you want collets for the horizontal you need to make a draw bar, just weld a chunk of 5/16 bolt to some 8mm threaded rod and feed it in from the front already screwed in to the collet.Then turn up a big long nut for the back

My drawbar is 5/16.

It would appear, from the yahoo forum site, that possibly some 2A machines were fitted with 5/16" drawbars. Not totally clear as there is often some doubt as to what the machine may have been originally (I believe some 2Amachines may have the nameplate but converted to a belt driven spindle -probably at a time of gearbox failure).

It appears, at present, that Centec and Centec 2 machines were all originally 5/16" and all 2B machines were 3/8".

As vertical heads were supplied for Centec 2 onwards, the Mkl vertical heads were likely all 5/16". All 2B machines would have been supplied with Mklll vertical heads, so 3/8". Anybody's guess as to the drawbar size(s) on the Mkll heads, but I'm sure Centec would have changed both horizontal and vertical drawbars to 3/8" at the same time. I would have thought that the change was made at the 2A, but whether at the introduction or mid-stream is not yet determined. I believe the 2B gearbox was uprated c/f the 2A. Motor power was increased for the 2B and that may be related to the changeover (both machines being built at the same time for a number of years).

There appears to be no definitive change-over date (from 5/16 to 3/8) at the present time. Boring a shaft to oversize may, or may not, be a good move. The shaft was likely well over-engineered in its day, so easily bored with no detriment. It does not need to be taken out to 3/8", even, if studding is used as a drawbar. The drawbar would need to be separable (or a blank taper fitted or collet could left in situ) should the machine be used in vertical mode if David's perfectly adequate solution is applied.

Most of this is currently a topic on the yahoo forum, of which you are a member. Perhaps Gary Wooding will chip in with some clarification - as he appears to be a very reliable and likely the best informed Centec owner.

I've tried using the yahoo forum ,to be honest it's not good ,will give it another go . I've ordered a 200mm 10mm drill bit to drill out the spindle ,boring it out 2mm shouldn't hurt the spindle there's plenty of metal there .

Sean

The trouble with old Centec mills is the parts swapping you can do on them.

There are 2 fixed vertical heads and also 2 versions of the Quill head. They all fit.

Centec 2 was sold on to Granville - all parts interchange, so Granville parts find their way onto Centec machines. Perhaps the Granvilles had a smaller drawbars. Granvilles did not have the Centec name on the castings.

'Lathes' has a photo of the very early vertical head and a few Granville machines.

All yahoo fora are a nightmare to navigate as far as I am concerned. The Centec one is compounded by the current site owner only putting up posts if and when it suits - sometimes days after the post was keyed in. Maybe that will change as the owner wants to abdicate. Non-appearance of posts leaves one wondering if they were lost in space, deleted or just several days late (by which time the posts show up the topic might be already covered by another member).