Super 7 - Best way to use ER25 Collets

Hi,

So, I was hoping for some advice. I want to get ER25 collets for my super 7. I see that I can get a chuck that would go on the thread of the outside of the spindle.

I also found that I could get a MT2 to ER25 collet adaptor that would go straight into the spindle and have a draw bar.

**LINK**

I think I would need to machine or buy a draw bar to work with the super 7, but I was wondering what would be the most accurate way of holding the work?

Any advice welcome. Many thanks Alex

Much the best is the first - a chuck that screws on to the spindle nose. This will allow you to pass long material through the headstock, and will have less overhang than the second, which is really intended for milling machines.

The best chucks are two-part. You screw the first part on the spindle nose and turn the (initially oversize) register to a close fit in the actual chuck bit which bolts on. This makes everything concentric to the spindle.

The second type has quite a lot of overhang (less rigidity), limits the length of work you can hold, and if the chuck you buy isn't quite true you're stuck with it.  

Whichever, drawbars are easy, just use a bit of studding and turn a top-hat collar to centre it in the back of the spindle.

Edited By John Haine on 02/06/2019 15:33:51

The obvious difference between the two types is that the MT holder will not allow long lengths of bar to be held through the mandrel.

I wouldn't think that either one was inherently more accurate than the other.

I use a collet chuck on my lathe and, because I can adjust it's back plate by tapping it to reduce error detected with a DTI) it's possible to centre collets very accurately. On the other hand, I have to tap the backplate to centre the chuck accurately, which is time wasted!

I imagine plugging an MT2 collet adaptor straight into the spindle would give good accuracy without messing about. The disadvantage is there's no way of tuning out any error if there is any. With hindsight, I would buy a collet adapter rather than fit a chuck, because it saves the bother of turning a back-plate.

I wouldn't bother machining a proper drawbar because a length of DIY Store M10 studding plus nut and washer would do the job. Cheap as chips. But a good looking drawbar would be easy enough to make.

Dave

I have fitted an ER25 collet to a backplate which has a loose register to allow fine tuning for runout as S-O-D has. I also have one with a 20mm straight shank to fit in an existing chuck,3 or 4 jaw. The fitting straight to the spindle taper is potentially better if you are lucky, as there is no way to correct any runout there might be, and the drawbar might get in the way sometimes with longer work.

Alright thank you everyone. I think it's clear that if setup correctly the MT2 to ER25 adapter is the superior method, but the fact that I can't put much material into the headstock and that it's much more difficult to adjust for errors. I think I will get the adapter with a backplate.

Many thanks all

Alex

Why not both?? My own choice is a chuck and a holder that enables collets to be shared with the milling machine, as the chucks and MT2 holders are less expensive than a selection of reasonable er25 collets.

Why both??

I use the chuck carefully lined up where accuracy is important and the mt collet holder where I wish to hold small diameters but time is more important than absolute accuracy or the need to handle long lengths- when producing a set of loco spring pins for example. An even quicker set-up could be a hex collet block held in the 3jaw and you could deal with long objects as well.

Edited By Nick Clarke 3 on 02/06/2019 16:50:13

Old mart,

My question is why bother with a register if it doesn’t? I thought the whole reason for a register was to get a precision fit every time? Spigots are there to add mechanical strength to the fixings (to reduce risk of shearing?).

I would go with a proper registered backplate and a carefully machined spigot for the chuck. If the actual ER chuck was off centre, send it back as ‘not fit for purpose’ (unless it came from bang good, of course.)

Alright so,

Does anyone have any suggestions of what to buy? I want my first option of using a chuck that fits on the spindle nose thread.

I see RDG do an option, but I'm not really sure I trust them. Everything they sell seems to be hit and miss.

Does anyone have a good website that I can buy from.

Many thanks

Alex

You can't go far wrong if you order from Arc Euro Trade. They have a very good reputation and everything that I have ordered from there has been excellent quality. Not the cheapest, maybe, but you know what they say about buying cheap . . . .

John

N D I Y , being able to fine tune at any time is an advantage as although the holder may run true, individual collets might have eccentricities. As for a loose register not being strong enough, the collet plate which I have is secured to the backplate with three 8mm shcs which are more than man enough for ER25. You must be terrified of using a mill when everything on the bed is just relying on friction to stop them moving.

I machined a back plated oversize for one of my chucks for this very reason. Only held with 3 M8 cap screws and never moved!

Jim

Hi John.

I've checked out the website, seems great. I don't mind spending a bit more for quality.

I looked at the chucks and what is the reason for choosing a larger sized one for ER25?

Or do the different sizes work for different lathes?

I'm sorry if these are mundane questions. This is my first foray into lathes. I know how to use them but the ones I use are ready to use. All I do is throw in my tool steel and roll!

Many thanks

First thing is to choose a backplate to suit the lathe. Arc Euro sell two threaded for Myford spindles, 4" diameter and 5" diameter. The backplate is drilled by the customer to make an adaptor by drilling holes to match those on the collet chuck: the two are bolted together and mounted as a unit on the spindle. The customer also turns a register on the backplate to fit into the recess on the back of the collet chuck.

I'd buy the middle collet chuck (95mm) to fit the 4" backplate, though the 100mm chuck is also a reasonable match (4" is 101.6mm). You can turn the backplate down to make it match the chuck if you want.

Dave

Alex, I have one similar to this **LINK** mine came from RDG made by HMB and it works extremely well. Being in need of another I found the one in the link, they do ER25 as well.

However I am in contact with the company making enquiries on several points see your PM for contact details

John

One of the backplates I use has been adapted to take a 4" chuck which was lying around and alternatively, the ER25 collet plate. 

I also can recommend Arceurotrade, they are also very quick delivering.

Edited By old mart on 03/06/2019 10:15:45

Unless you already have ER25 collets, maybe you should consider getting a larger size? I use ER40 on my big-bore S7 as you can hold 26 mm stock in it, if your lathe is standard bore ER32 may give you a wider size range than ER25.

I had the MT2 adapter. It was ok for just short things. I chopped off the MT2 part and just hold it in the 3 Jaw chuck now. Very happy with it. I can put upto 5/8 stock through the S7 spindle into the collet chuck if needed.

I also have the smaller ER11 on a parallel shank to also go into the 3 jaw chuck.I use the ER11 for stuff under 7mm diameter. The bigger parts go into the larger ER20 or ER32 holders. The collet size I use the most on the things I make is the ER11 and most used in the 3,4,5,6mm collets.

The face plate mounted collet block I did not like very much. What I did not like about it, was the bed going forward over the gap area of the Myford lathe. With the collet holders in the 3 jaw chuck, the saddle never gets to the edge of the lathe bed. The Mt2 part was turned into a stop for the 3 jaw chuck and Er32 collet adapter.

Neil

If your lathe has a 2MT mandrel, and you want to pass work through the mandrel, there is less point in buying a chuck larger than ER25, (which hold up to 16 mm-which is bigger than the bore of the Mandrel )

If you have the 4MT Mandrel then ER32 collets go up to 20mm, ER40 to 26mm. But the larger sizes do not cover the smallest sizes ( ER25 - 1 mm, ER32 - 2mm, ER40 - 3mm)

If you really want to have work absolutely central, then a 4 Jaw Chuck and a Finger Clock is the route to take.

But Collets should provide a quick and easily repeatable way of holding work central.

The ER system has the advantage that the Extended Range allows Metric or Imperial material to be held in the same collet, within limits. Usually the range is 1mm in the larger sizes, 0.5mm in the smaller

Howard

I'll add my 2pennyworh, just watched 3 you tube videos by 'Ades workshop' on his trials mounting & using ER 32 collets, bottom line is you can normally work around a less than perfect collet chuck but if the collets do not have decent concentricity you are stuffed.

BTW Cutwel do a standard collet & a super precision offering.

Tony