ER Collet with low TIR? Advice required

[Kevin MuirParticipant @kevinmuir57996]

Hi folks, I am new to this forum but have enjoyed reading a lot of great posts on the forum for a while.

I have been using my 41/2" Boxford lathe for many years and now need some advice regarding collets for a mill and also for my Boxford.

I am looking for a set of ER25 collets for the Mill, I have a couple of collets but would like a full set to ensure the best accuracy while using drills and reamers in the mill.

I have read all of the posts on the forum about ER collets but I am really looking for feedback from people who have bought ER collets and can confirm how accurate they are and from which seller. There are some amazing deals for the ER collets about but are they just junk and a waste of money or can they compete with higer priced sets. Are you getting a significantly better product by spending three or four times the price?

I am also looking to make a collet holder for the Boxford with either ER32 (like the one Double Boost made, great video on Youtube) or possibly ER40 collets. While the Boxford can only accept about 20mm through the headstock, the use of ER40 collets would allow me to grip up to 1" diameter bar which would be great.

Has anyone tried both ER 32 and ER40 collet systems on their Boxford?

Sorry for the long winded first post.

regards

Kevin.

[Kevin MuirParticipant @kevinmuir57996]

[Bob Brown 1Participant @bobbrown1]

I use ER40 collets on my Boxford AUD (metric) with a back plate like these **LINK** do not think I purchased the chuck from them they are just one supplier for this type.

I do not think there is any thing to be gained in making the chuck yourself as they are not that expensive.

As for run out that is less than 0.01mm which is good enough for me but you need to make sure the collets and holder are clean as a tiny bit if swarf can cause them to run out.

Bob

BTW ER40 will go to 30mm

Edited By Bob Brown 1 on 09/01/2015 08:09:00

[John HaineParticipant @johnhaine32865]

Bob, I use ER40 on my Super 7 with a chuck supplied by Myford. The one they made required you to machine a fitting in situ on the lathe for best concentricity. The collets I bought from Collets Direct, good price and they did a deal on a set. I want to buy some more to go smaller than 16 mm. I would say the TIR isn't wonderful especially when the collet is closed a lot below its nominal size. If you work in Imperial I would suggest getting a couple of the standard imperial sizes as well as Metric – I have done this with an ER16 set I use on my Novamill, as it can be quite difficult to securely grip certain imperial sizes in metric collets. One example is 1/4 inch in a 7 mm collet, and I suspect 3/4 wouldn't be so good in a 20mm one. Provided the chuck has very good TIR then you could always buy a set of Regofix collets, I believe they invented them, but they're Swiss and I suspect very pricey!

[Jon GibbsParticipant @jongibbs59756]

Hi Kevin,

I bought the collets, nut and spanner from Arc and made my own ER32 collet chuck using Harold Hall's brilliant instructions. I also made an ER20 collet chuck too as I had the collets already. **LINK**

I learned a lot from doing it myself and the results were pretty good too.

Jon

[Neil WyattModerator @neilwyatt]

The ER collets from the hobby suppliers are good to within 0.001"/0.025mm.

More accurate collets can be obtained, but at significant cost. Bear in mind that the runout of the mill spindle taper is the limiting factor and the Schlesinger limit for mill taper runout is 0.01mm and similarly for 'finish turning lathes' so paying for more accurate collets than that is probably pointless unless you have a true 'toolroom' lathe

Neil

[Russell EberhardtParticipant @russelleberhardt48058]

Like Jon, I bought the collets and nut from ARC and made the chuck myself for my Atlas which has the same spindle nose as the Boxford. Making a chuck that screws directly onto the nose has several advantages to my mind. It reduces overhang, eliminates the backplate/chuck interface, and, if you finish the taper in situ, ensures accuracy.

I happen to have a 7/8 mm collet on the lathe at present so I just put some 5/16 in silver steel in it and checked with a dial gauge. I have 0.0001 TIR close to the chuck and 0.0005 at about 3 in away so well within Neil's limit.

Russell.

P.S. the TIR figures are in inches

Edited By Russell Eberhardt on 09/01/2015 09:40:17

[mechman48Participant @mechman48]

I bought a set of metric ER 25 from CTC tools (usual disc.) plus a MT2 & MT 4 chucks; I use the MT2 in my mill, the MT4 in the headstock of my WM250 with a draw bar fixing. I haven't got a collet chuck per se as am of the opinion that its extra overhang plus any inherent run out would compound itself so having the MT fixing would keep it closer to the headstock & minimise any overhang. I have got a set of imperial ER 25 collets (set of 5  ) for a Christmas prezzie to cover some smaller imperial sizes that the metric set won't cover…  1/8" – 1/2" .. I haven't had any DTI on it lately but will do a double check & post figures, just my preference at the mo' .

George

Edited By mechman48 on 10/01/2015 11:11:19

[John HinkleyParticipant @johnhinkley26699]

Like George, I, too, have bought both ER25 and ER32 collet sets and chucks from CTC. Current price for these are £25 and £40 for the collet sets. Chucks on top of that, then P&P extra. Still good value in my opinion. They also do precision ground collet sets with a claimed runout of 0.008mm. I would suggest that unless you are making scientific instruments or models in nano scale, that would be rather over-the-top. I think I'm doing well if I can get within 0.1mm of a desired measurement!

John

[John HaineParticipant @johnhaine32865]

For lathe work holding you don't want a collet chuck on a taper but one that fits like a normal lathe chuck. Then you can get lower TIR especially if you machine it in situ, and pass the stock through the spindle.

[Kevin MuirParticipant @kevinmuir57996]

Many thanks for all of the advice.

I will let you know how I get on with the collets.

Before I but a regular set of ER25 collets in 1.0mm steps, I thought I would ask one last question about them. I noticed a supplier was offering ER 25 collets in 0.5mm steps, is there any advantage in buying these over the regular 1.0mm step metric collets and a few Imperial collets? Are there any sizes the 1.0mm step metric collets struggle with?

I am milling a block (25mm x 50mm x 34mm) of titanium nto a rather odd shape on the dividing head, "what a tedious job". After reading all the horror stories about milling Titanium I have been taking very small cuts and using lots of oil applied with a small brush.

I think that my approach may have been too cautious but It is working out fairly well with almost no heat in the part I am making.

I have to make one final finish pass with an 8mm carbide ball end cutter on all of the curved faces to get the surface finish I am looking for, hence the request for information on ER collets. I will buy a whole set rather than just the collet I require for this job as I can use them in the tailstock of the lathe for accurate drilling and reaming. Hopefully the final product will be worth it.

Thanks again for you advice.

Kevin.

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