SPG Tools

Can anyone give a recommendation for a SPG 9512B milling machine with a R8 chuck please.

cheers

Martin

Looks like a Sieg Clone. Most of these small mills in this range are OK for smaller work. Not as rigid as bigger machines so smaller cuts and a bit of care needed. I have a Chester Conquest which is similar. It is a good little machine. I have made many tools with it including a dividing head, several BXA tool holders and much more. Used with a good collett holder it should be OK.

Probably a RealBull machine

They arent bad but not very rigid ,a very solid bench will help alot.

The gears would drive you mad ,hence buy or make your own belt drive and strip out the gears.

The tilting column is a pain ,best to brace it somehow at the back where it joins to the base with a thick steel /aluminium plate.

Possibly fit a gas strut of some kind to make the raising lowering of the head easier.

Picture of mine below.

I also replaced the cracked and torn rubber covers with homemade ones made out of  rubber coated kevlar material.

I replaced the headstock bearings with taper roller bearings. (did the same with my chester conquest mini lathe that i used to own )

The most annoying part is the fine feed,they may have improved but mines always been a pain. Has a habit of suddenly dropping and digging in to the work.

All that said ive had my warco version for around 15 years or more and its been ok for small stuff .

i have a bigger alexander gha mill now (still collecting tooling) so im using this less and less now.

The mill is /was originally made by real bull and known under various guises such as xj12-300 .

Some guy here has wrote a decent review and made similar alterations.

**LINK**

Edited By mark smith 20 on 29/10/2017 10:20:31

Edited By mark smith 20 on 29/10/2017 10:30:12

Edited By mark smith 20 on 29/10/2017 10:46:46

Many thanks to all, the review was quite interesting, the thing I like about it is that you can have a R8 chuck at no extra cost and as I am picking up by reading comments it is the way forward, as I am only thinking of doing small ali stuff for airguns it would seem sufficient for my needs and I also have a vertical slide on my ML7 as back up.

Cheers

Martin

I think you will find the chuck is £60 and NO EXTRA POSTAGE when bought with a machine. Also be aware that those chucks are not ER chucks but a far eastern collet chuck which can be hard to find extra collets to fit.

Other suppliers will usually put any tooling purchased at the same time into the crate to save you postage.

I ment that it has the R8 spindle fitted instead of a MT as most other small mills have and you have to buy the collet set extra from either them or any other supplier, I guess I should have said spindle not chuck in my post but I'm new to this game and sometimes use the wrong term.

Cheers

Martin

The fine feed on my warco xj12-300 has just decided to stop working 1/3 of the way through scribing graduations on a handwheel im making. Its just spinning around

Just removed the fine feed looks like the middle areas of the teeth on the worm gear are mangled .? Anyone know where i can get a replacement?

Thanks

If anyones interested one of the advertisers on here has them in stock at around £34 (with shipping and vat) , sounds a bit expensive to me compared to spares for the seig mills from arc.

The parts only 32mm diameter by 22mm long.Its not a proper worm gear either just probably a metric helical gear of some kind but i dont know anything about mod gears.

Does this sound expensive to anyone else??

Edited By mark smith 20 on 31/10/2017 10:34:39

It sure isn't a worm wheel! I'm not even sure it is a helical gear. If it is helical the teeth ought to slope to one side, or t'other, at the helix angle of the worm. It's not easy to to tell from the picture if this is the case. If it's a straight spur gear then in theory it will only have point contact, which is probably why it is worn. For a spur gear to mate with a worm the axes need to be moved from a right angle by the helix angle of the worm. I wonder if even this was fudged, and the gears mated at 90°, as the gear only appears to be worn in the centre of the teeth?

The DP/Mod of the gear will be determined by that of the worm. Assuming that the pitch of the worm thread is rational, say 3mm, then the DP/Mod of the gear will be irrational as pi will be a factor. Or in other words the gear will not have a standard DP/Mod value.

Having said all that, the gear teeth don't look that bad. Are you sure the worm/gear is the issue?

Andrew

Mark,

Before spending £34 on a direct replacement, I would have a very close look at the design and execution of the gear pair. .... It appears, from your photograph, that the depthing is way too low: I can't see any other reason why [with no missing teeth] the mechanism should just spin freely.

Big Question: Is the depthing adjustable ?

MichaelG.

.

Edit: My post crossed with Andrew's ... but I think we're on the same wavelength.

Edited By Michael Gilligan on 31/10/2017 10:55:16

Hi Andrew, the teeth are at an angle but only a few degrees. The worm shaft does only touch very slightly in the middle which is probably why they are such a pain to use and now it seems it is mangled in the middle and just totally slipping when turned as there is no contact.

I dont like the idea of buying another which will probably be just as bad after a few months of use.

I`ll take some measurements of the gear and teeth . The teeth maybe dont look too bad but if the worm shaft is only making contact at the very edge of the middle then its not really designed properly.

Thanks

Hi Andrew, yes the worm shaft and gear make very little contact , ive always had a problem of the fine feed suddenly tightening up then dropping too far. I just put it down to Chinese manufacture.

When i push the worm shaft teeth into the gear in my hands ,there is around a 1mm gap at the bottom which doesnt sound ideal.

The block at the handwheel end as a bit of wiggle room so that tightening the block pushed downwards has a tendency to push the gear end into the worm gear but not by much.Nothing is a tight remotely precision fit.

here a few more pictures .

The pitch of the gear is around 3mm as best as i can tell ,with 29 teeth and a outside diameter of 30.90mm.

Edited By mark smith 20 on 31/10/2017 12:32:32

Mark,

Thanks for posting the photos.

On that evidence, I would recommend that you buy a decent worm-wheel [to suit the available centre distance and the existing worm]: Then adapt it to suit.

Note ... If the worm is a difficult pitch it might be better to buy the pair.

MichaelG.

It looks like you have 'good' tooth still at the outer end away from the dog. You can prolong its use by

A) machine off much of the dog teeth,
B)recut the dog teeth deeper which is a low precision job possible even if you don't have a rotary table,
C) turn off some of the gear teeth edge beside the dog
D) make a thick washer to take up the slack for the bit you cut off

A bit of measurement and good photos would make a good write up for MEW for other owners and earn you the cost of the cutter to make a replacement.

I think the above is easier/cheaper for any beginners than making a new gear though the follow up article could be doing that.

Interesting approach, Bazyle

But, I think the underlying problem is simply that the mesh is too shallow; in which case [unless that is corrected], the repair would be 'Bad as New'.

I do agree though that writing-up whatever Mark does to fix this should be of interest to many.

MichaelG.

Andrew ,i have thought of buying a helical gear but the angles of the the teeth are usually steeper on the common off the shelf ones such as from HP Gears (17 degrees or something) ,this one looks like only around 3 degrees.

I could of just turn off the teeth part of the original and bored and glued on a rplacement bit.

Bazyle , i did wonder about that you mentioned , problem is the teeth should ideally engage alot more than they do even if the part wasnt worn and it causes a lot of slack and backlash which id rather not have on the fine feed.

When i look at the worm gear it probably is a mod 1 worm gear but without the hobbing just cut straight across. Also size seems to fit with the standard off the shelf versions but they have 30 teeth not the odd 29 teeth as this has.

Such as this **LINK**

the dimension seem about right apart from the tooth number.

I was thinking it was a helical gear but the angles are too shallow.

Could you bore out the block and fit an eccentric insert to lower the worm onto the wheel?  Or perhaps more simply lower the entire block slightly by elongating the fixing holes?

Brian

Edited By Brian G on 31/10/2017 14:50:13