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Member postings for Mark Davison 1

Here is a list of all the postings Mark Davison 1 has made in our forums. Click on a thread name to jump to the thread.

Thread: Anybody familiar with OZ25 collets?
16/12/2019 21:09:49


16/12/2019 21:01:07

Its NOT OZ25 after all. I found out the hard way, bought another only to find out it doesnt fit (too small).


Can anyone help identify this?






Edited By Mark Davison 1 on 16/12/2019 21:10:22

08/12/2019 21:59:53

I recently bought a harrison vertical mill that came with an Osborn tools collet chuck with a single collect inside it. It looks a bit like an ER collet but I believe it may be an OZ25 collet chuck. The taper appears slightly less than on an er collet and the length slightly longer. The collet appear to have an internal bore of 1", but the are no markings on the collet itself. Does anyone know what the clamping range of one of these collets is, is it likely to hold a 25mm dia end mill? ER collets have a stated range of 1mm but I cant find much info on these.

Thread: VFD off the bay
28/11/2019 22:25:07

I have 2 fake cheap no name clone VFDs from Banggood, about £55 each delivered from China. I would normally buy products from close to the top of the range but took a punt on one of these instead of an Optidrive. I must say, for the money I cant fault them. Neither gets hot, run the motors quiet happily etc. They don't do vector control but neither the lathe of mill motors get a hard life (3hp and 2hp respectively). I've just bought a new mill so will try a branded VFD with proper braking and sensorless vector control on the lathe and move the cheap one to the new mill, but it isn't going to be easy to justify the extra expense.

Thread: How do I remove the motor from a Harrison vertical mill?
18/11/2019 22:37:58

The VFDs I have are (supposedly) 2.2kw and the motor is only 1.5kw. What happened to yours Dave?

18/11/2019 22:36:24

I think I've found the start point ?


Should there still only be 3 wires even on a 6 pole motor ?

17/11/2019 20:10:08

Finally managed to get the motor out. I was going about it the right way but had got the foot pedal lever hook behind something which was jamming it. Its enormous! 100L frame with 28mm shaft, 6 pole, physically huge (and heavy) for a 2hp motor.

I've got a couple of the generic chinese VFDs that look identical, but mine don't step up the voltage. I'll see if I can get the windings on this one modified, if it isn't successful I'll modify the mounting plate to take my spare dual voltage 2hp 4 pole motor and buy a 24mm to 28mm shaft adapter.

17/11/2019 07:42:37

That's why I need to dig out the star point in the winding and bring it to the junction box. Most modern 3 phase motors are dual voltage, switching between star and delta configuration. You can convert older motors if you can find the star point without destroying the winding.

16/11/2019 18:09:54

It is NOT the same as the horizontal mill.

The motor is hinged from a great steel plate the bolts to the RH side of the cabinet. There is a foot pedal at the back that raises the motor on the hinge via a linkage. Im assuming I pull the entire plate and hinge mechanism out of the side with the motor still attached, but cant work out how to undo the linkage.

Anyone tackled this job before?

I need to dig out the star point as it isn't a dual voltage motor and I want to run it from a VFD.

Thread: Bantam - warped compound gib
12/11/2019 18:40:13

I've almost managed to straighten it (G clamp). It was out by 0.015" in the centre and was bowed in both axis and even has a slight twist. It was more like 7.5" in length, not 6". Still some tweeking and no doubt some lapping/sanding, but getting there.

A new one was best part of £100 plus p&p and plus vat. I should be grateful it's still an option I guess.

Edited By Mark Davison 1 on 12/11/2019 18:41:38

11/11/2019 16:08:45

Convex (touches the slide in the middle and the stationary bit only at the ends). It is anything but thin and flexible. The only way the screws will straighten it is to wind in the adjusters at either end, which will place pressure on the middle until it bends, causing it to go very tight in the process. In fact it is so tight in the middle even without adjusting the screws that i cant reassemble it.

11/11/2019 14:45:50

Thanks all

I think it is steel, but could be wrong.

It has 3 square sides and one angled, as opposed to two sets of parallel faces. I suspect it has bowed in 2 axis, not just the one. I have a surface plate but have yet placed on it to measure it. May do that this evening.

The mounting holes are out of alignment now (although not so much that the screws wont go in), bending it back would put them back in the right position.

11/11/2019 08:48:26

I wasnt completely happy with the feel of the compound slide on my colchester bantam, so disassembled it for cleaning and adjusting. It is in excellent condition with one exception, the gib is slightly warped. I assume this happened during manufacturing as a result of machining the angle with residual stress in the material causing it to distort. Surprised it has been working as well as it has, although it wasnt evident until I loosened the bolts.

What are my chances of straightening it? Haven't yet measured it but suspect .005", possibly as much as 0.010" over 6". The main bit that concerns me is that it has 4 large holes in it to bolt it to the compound with cap screws so worried it wont bend evenly.

Thread: INT30 sensitive drilling attachment
10/11/2019 08:34:57

Sorry, you may have done, I jumped straight into the drawing!

I'm going to go the 'Schaublin route' as you've suggested. Only drawback will be the time it takes to mount/unmount the nose plate and I think i can live with that. I'm just trying to decide if i buy a cheap ER20 straight shank collet chuck ( £13 +VAT from cutwel) and thread the rest of the shaft into that, or turn the whole thing from 1" EN8 bar that I already have.

09/11/2019 09:38:15
Posted by DC31k on 31/10/2019 16:42:49:

Have a look at how Schaublin do their sensitive drilling attachment for the 30 taper spindle on the 13 mill.

It locates on the spindle nose itself, like a big facemill would.

Much easier to make than something that locates in the taper.

You need to think of how the drive will be transmitted while still allowing sliding movement. Generally done with a key and keyway. A dog point grub screw into the 3MT adaptor could be used, but requires tapping a hard part. An accurate keyway is equally difficult in a hardened ER straight shank chuck.

Copying the Schaublin design would allow you to put keyway in unhardened spindle nose adapter and use angle grinder to form a not-very-precise-over-wide slot in ER chuck and then JB Weld in a key (using the adapter to keep it aligned while it sets).

See bottom left of page 6 here: (Anglo-Swiss Tools, Schaublin 13, French catalogue)

for nose dimensions. Top right of page 12 for attachment complete.

I have a drawing for all the Schaublin parts so if you PM me with contact details, I can send to you.

I've finally got my head round what you meant when you said mount directly to the spindle nose. I still haven't got the mill (long story involving haulage company) so hadn't realised there are 4 threaded holes in the nose. The bit I still cant picture, even after study the drawing you sent (thankyou) is which way up the adapter mounts to the nose. I'd have assumed the ground face mates with the nose but the assembly drawing suggests it goes the other way, with he ground face down?

03/11/2019 19:03:34

Too big, but interesting

01/11/2019 20:35:05

Thanks for the suggestions. I was hoping to use at least some of the depth of the INT30 taper so as not to loose too much of the available height. Once I collect it next week I'll see how important that is. I have a lathe and a MT3 boring head so will need to buy an INT30 one anyway.

31/10/2019 08:20:07

I've just bought a Harrison vertical mill with INT30 spindle (although not yet collected it).

I bought this despite being reluctant to buy a mill without a quill, primarily as I don't have the height for a Bridgeport type machine. I want to be able to do some drilling on the machine and stumbled across this on **LINK**

I'm looking to make something like this but using a straight shank ER collect chuck inserted directly into an INT30 to MT3 adapter (such as the one below - 87mm long extension) that has had the morse taper bored out to a parallel 25mm hole. What are my chances of boring out this supposedly hardened INT30 adapter with carbide tooling and getting a satisfactory surface finish? Or should I sleeve after boring, say with brass, and then bore that?

Thread: Repair required for Milling Knee
06/09/2019 20:34:08

I have two of these, the same English made bench version you have pictured and a floor standing import. The import had a cracked main casting when I bought it (pics in gallery). Personally I'd glue, drill and tap. It you still want to braze it at a later date you could. If the braze goes wrong now the knee will be scrap.

Thread: Bantam cross slide end float
24/08/2019 18:24:32

Sorted, almost. I think the splines were just so tight it made fine adjustment almost impossible. I tried it on the press and manage to get rid of the float. Press the shaft in and out a couple of times and then tried it in situ and got close enough for now (it is ever so slightly too close now).

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