Looking for advice on ER16 collets

John Palmer
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Looking for advice on ER16 collets

Postby John Palmer » Mon Nov 05, 2012 5:39 pm

I have just placed an order for an ER16 collet chuck for use with my ancient Unimat, and should be grateful for any views people have about the choice of collets to be used with this.

I was surprised to find just how wide a price variation there is for ER16 collets – prices range from about £4.00 to £15.00 per collet or more. I imagine those at the low end of this range may be cheap and cheerful Chinese imports, though this doesn’t disqualify them from consideration if the benefits of more expensive collets from European manufacturers are only marginal.

Other things being equal I’m inclined to buy from a supplier/manufacturer who can provide both English and metric sizes. We seem to have ended up indiscriminately mixing measurement systems on our models – 1/8th and 2mm axles being the obvious example - so I have a need for both.

Thoughts/recommendations welcome!

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Wizard of the Moor
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Re: Looking for advice on ER16 collets

Postby Wizard of the Moor » Mon Nov 05, 2012 7:21 pm

There was an interesting article by Harold Hall in last month's Model Engineers Workshop looking at ER collets.

The general implication was that the less expensive collets are not slit as deeply as the "standard" and are thus more difficult to tighten. This becomes relevant where you want to grip a 1/8" axle in a 3-4mm collet, i.e., the work is near the lower end of the clamping range.

You could try talking to Peatol, as they offer an ER16 spindle for their machines. I'm not sure whose collets are supplied though.
James Dickie

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45609
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Re: Looking for advice on ER16 collets

Postby 45609 » Mon Nov 05, 2012 7:30 pm

Hello John,

I have been using a set of ER16s and collet chuck on my Unimat 3 for a number of years. My set is a 10 piece metric and come in 1mm steps. 1mm, 2mm etc... up to 10mm. I bought this set from Chronos but is seems they no longer do a suitable chuck to fit straight onto the Unimat 3 spindle nose.

http://www.chronos.ltd.uk/

The ER collets are useful because they have quite a range when holding work but I have found that the 2mm collet cannot be compressed enough to hold say 1.1 to 1.5mm diameter stock. Trying to approach it from the other direction the 1mm collet cannot be expanded sufficiently. 1.1mm is very tight and hard to extract after machining. I found out recently that Arceurotrade can supply ER16s in 0.5mm steps for the small sizes and do a 12 piece set. They also do imperial sizes.

http://www.arceurotrade.co.uk/Catalogue/Collets/ER-Collets-Collet-Chucks/ER16-Collets-Collet-Chucks

The limitation I have found is the max diameter is only 10mm so if I were buying again I'd go for ER25 or ER32 as this gives more capacity and it seems that there is more fixturing available for the large collets. ER25 now seems to be the size offered by the importer of the Emco range.

http://www.emcomachinetools.co.uk/EnterShop/tabid/268/List/1/ProductID/424/Default.aspx?SortField=UnitCost+DESC%2cProductNumber

When I need more capacity I'm using #2 Morse Taper collets on a Myford. Here I prefer the original Myford type as they have no restriction on the length of bar that can be held.

Cheers....Morgan

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Tim V
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Re: Looking for advice on ER16 collets

Postby Tim V » Mon Nov 05, 2012 8:25 pm

I use WW 8mm collets on my Unimat, and ER20 collets on the Myford.
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John Palmer
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Re: Looking for advice on ER16 collets

Postby John Palmer » Tue Nov 06, 2012 12:50 am

Thanks, chaps, for the interesting and helpful comments so far.

The comments about clamping range are particularly interesting and confirm my thoughts that what I need is a mix of English and metric collets.

My brief initial trawl of the internet for relevant guidance included a suggestion that at the bottom end of the clamping range for any given collet the item being held is in minimal contact with the collet’s ‘segments’. So, with regard to James’ point about clamping 1/8th material in a 3-4mm collet, the better solution must be to get a 1/8th collet rather than relying on inferior clamping with the metric equivalent.

Morgan, I was attracted to Arceurotrade as supplier precisely because they offered both English and metric sizes. The price looked acceptable, too, occupying the middle ground between dirt cheap (=suspect in quality?) and the very expensive German collets. Anyone have any hands-on experience of collets from this supplier?

One bit of advice I’ve come across is that it’s OK to draw down onto an item smaller than the collet’s nominal capacity, but trying to accommodate anything larger than nominal capacity is likely to be a recipe for a ruined collet.

As to Morgan’s observation that Chronos no longer do a collet chuck for the Unimat 3 spindle nose, I was pleased and surprised to find that currently they do have some in stock – which is just what prompted me to place my order for one. Many years ago I did make my own collet chuck for the Unimat, but of course the collets I made suffered from being BMS with no hardening, hence I’m now seizing the opportunity to get something better, with the option to purchase additional collets when required. In fact, I suspect the best purchasing strategy may be to buy the particular collets you need when you need them, rather than incurring the cost of a full set that is likely to include some you’ll never use.

Tim, I do like what I’ve seen of the setup for WW collets, and if I were ever to make a collet holder for small diameters again I think I’d go for the hollow drawbar through the spindle arrangement, which must be good for repetitive work where you need to keep feeding fresh bar stock forward.

Although there are occasions when it would be nice to have a machine with more grunt than the Unimat, I’ve found it entirely adequate for the great majority of machining work I’ve ever had to do. Realistically, the occasions on which I shall need to mount something outside the capacity of an ER16 series collet will be so few that I might as well save my money and clock the job in a 4-jaw chuck.

Philip Hall
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Re: Looking for advice on ER16 collets

Postby Philip Hall » Tue Nov 06, 2012 9:37 am

If I might jump onto John's enquiry, does anyone know of a collet chuck that will fit the 12mm thread of a Unimat SL spindle? I can find nothing currently available (hardly surprising given the age of the lathe).

Philip

Clive Impey
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Re: Looking for advice on ER16 collets

Postby Clive Impey » Wed Nov 07, 2012 6:56 pm

Philip Hall wrote:If I might jump onto John's enquiry, does anyone know of a collet chuck that will fit the 12mm thread of a Unimat SL spindle? I can find nothing currently available (hardly surprising given the age of the lathe).

Philip


Phillip try http://www.emcomachinetools.co.uk . They list spares for the Unimat SL which include a collet chuck and an email to them will confirm availability and price. Failing this if you want to make your own chuck Tracy Tools Ltd TracyTools.com have 12.0mm x 1.0mm taps and dies.

Clivelincs

Philip Hall
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Re: Looking for advice on ER16 collets

Postby Philip Hall » Fri Nov 09, 2012 9:49 pm

Thanks Clive.

I emailed them but they don't do one now. I've actually dealt with them before as supplier of drive belts, but didn't recognise the web address. There might be second hand ones out there, but the problem would then be of wear and how accurate they actually are.

Philip

John Palmer
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Re: Looking for advice on ER16 collets

Postby John Palmer » Sat Nov 10, 2012 4:58 pm

Took the plunge and went for the Arc Euro Trade collets.

Their server auto-emailed acknowledgment of order at 13.27 on Friday 9th November - Items dropped through my letterbox about 10.00 today. No complaints about speed of service!

In the end I settled for an initial purchase of 2mm, 1/8" and ¼" collets, as this covers the usual axle diameters plus the shank size of my elderly set of end mills.

Philip, tooling for the SL seems to be hard to come by these days. I came across an ebay seller who is currently offering what seems likely to be an original Maier+Co collet chuck plus 9 collets for the SL – the relevant URL is http://www.ebay.co.uk/itm/EMCO-UNIMAT-SL-DB-COLLET-CHUCK-COLLETS-/121010293852. This is not the first such chuck offered by this seller, but the prices offered seem to be going up. Also, as the seller acknowledges, the item currently offered has suffered minor damage, which might raise a suspicion that the chuck hasn’t received the best of care.

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Tim V
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Re: Looking for advice on ER16 collets

Postby Tim V » Sat Nov 10, 2012 5:14 pm

Philip

Arc Euro Trade list an ER16 holder at £14.95, with a back plate. Should be relatively simple to machine up a plate to fit on your machine to take this back plate.
Tim V
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John Palmer
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Re: Looking for advice on ER16 collets

Postby John Palmer » Sat Nov 10, 2012 6:04 pm

Another possible chuck is available from Hardpoint Industries via Amazon USA, accessible via this URL: http://www.amazon.com/gp/product/B006KOGD2Y?ie=UTF8&seller=A2WFPY6XLCB2DR&sn=Hardpoint%20Industries

Alternatively, why not consider reproducing the watchmaker’s collet sleeve that Maier originally offered for the SL? You get a good impression of this accessory’s components from the manual, available online if you don’t still have one of your own.

To my way of thinking, the potential difficulty of fitting a backplate-mounted collet holder would lie in getting it accurately aligned along the same axis as the spindle. If you can make up a receiver blank and screw it onto the spindle nose, you can then ensure such concentricity by machining the taper to receive the collets into this blank whilst it is attached to the spindle – necessarily the resulting taper cone must be concentric with the spindle axis.

Philip Hall
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Re: Looking for advice on ER16 collets

Postby Philip Hall » Mon Nov 12, 2012 12:36 pm

Thanks Tim & John.

I quite like the idea of the Hardpoint Industries milling chuck. I'm still feeling my way with this, so I presume any make of ER 16 collets will fit this? Arc Euro would be my choice of these, given their prices. It does seem like an economical way to go. I am anxious that any result will be more accurate than my Sherline 3 - jaw chuck, which is only about 1.25 - 1.5 thou out. Am I chasing rainbows here, given the limitations of the SL?

Philip

John Palmer
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Re: Looking for advice on ER16 collets

Postby John Palmer » Fri Nov 16, 2012 1:14 am

Philip’s last post set me wondering about the accuracy of my own equipment, so I did some testing of it with a dial indicator.

First discovery was that I have an indicated runout of 0005" on the spindle nose, so all chucks fitted to it will be susceptible this error, whatever its actual magnitude may be. If it is an error then it may have the effect either of exaggerating or cancelling out any runout in chucks attached to the spindle.

Next I tested both my Maier-supplied 3-jaw chuck and the collet chuck newly purchased from Chronos. The 3-jaw fairly consistently returned an error in a range between 001" and about 0015". The 1/4" collet, however, returned errors in a slightly larger range that I estimated to have been between .0015" and .0022". This was an entirely agreeable result for the 3-jaw chuck and one that was distinctly disappointing – and unexpected - in the case of the collet.

As nothing more than an enthusiastic amateur user of machine tools, I admit to ignorance of what I should make of my findings. Furthermore I’m not sure how far I can place any reliance upon them because they may have been affected by various factors over which I had no control and which I cannot check (e.g. accuracy of indicator, possible irregularity of test pieces, impact of surface finish).

In the light of this, Philip, I think you are quite right to wonder whether you’re chasing rainbows. And before you commit to the Hardpoint collet holder you might want to reflect upon the Amazon reviewer’s comment that the SL spindle required some thread relief. I wasn’t clear about what the reviewer thought was necessary, but wouldn’t be in a hurry to start carving into the spindle if it were my lathe.

Since I’m one of the three refugees from the Avon & Somerset Group assisting with New Mere at Portsmouth, perhaps we’ll get an opportunity to compare notes on Saturday.

Alan Turner
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Re: Looking for advice on ER16 collets

Postby Alan Turner » Fri Nov 16, 2012 8:21 am

I think you need to be a bit careful about what you are calling different components. A milling chuck that takes collets is meant for milling. It is probably no more accurate than a chuck.

A collet chuck is normally supplied "unfinished" and the final machining is done on the machine it will be used on. That way it takes out any runout of the machine and runs true for that machine.

Regards

Alan

Philip Hall
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Re: Looking for advice on ER16 collets

Postby Philip Hall » Fri Nov 16, 2012 10:09 am

I've taken the chance on the Hardpoint Industries milling chuck, on the basis that it was only $24.99 (plus the shipping of course) so it wouldn't be the end of the world if it wasn't up to much. Also, one of the other reasons I wanted a collet holder was for hand turning small parts; a collet chuck seems to me to be safer than a three jaw whizzing around near your fingers. So if it's not as accurate as I would like I can still use it for that. However, I may just be lucky!

The other possibility would be to mount a collet chuck onto the Unimat faceplate as Tim suggested, but a model engineering friend has pointed out that turning a register on the faceplate is not for the faint hearted on a Unimat SL! But that will be the way to go if I want near perfect accuracy. Then the fact that the chuck will be a fair way from the spindle nose comes into play!

I also asked my engineering friend about collet quality, and he was quite clear that the more you pay...

I'll look out for you, John, at Portsmouth.

Philip

Alan Turner
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Re: Looking for advice on ER16 collets

Postby Alan Turner » Fri Nov 16, 2012 1:34 pm

Best take note of this (to be found at the bottom of the page):

"This item fits, but needs a thread relief for the Unimat spindle thread so the collet chuck doesn't just shank out."

regards

Alan

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Tim V
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Re: Looking for advice on ER16 collets

Postby Tim V » Fri Nov 16, 2012 4:07 pm

I have read somewhere, that it is normal to skim the face of the Unimat nose, to ensure it's accurately aligned with the cross slide.

I've done it on mine, the nose is soft steel.
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