Home-made collet chuck and collets - some Q's

Home Model Engine Machinist Forum

Help Support Home Model Engine Machinist Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Frankly, they are fine for holding PRECISE dimensions but are liable to crack if undersize stock is used.

[SNIP]

My reading of a wider field than most!

Norm, if you're going to make a bold point by SHOUTING it at us in all caps, then later pat yourself on the back for your knowledge, you may want to get the terms correct. Precision is repeatability, accuracy is getting close to the target. If I throw 10 darts aiming at the bullseye of a dartboard and they all end up in triple eleven, then I am being very precise but I have poor accuracy. However, if I hit the bullseye one in three times, my accuracy isn't too bad but my precision is off. So a ground bar can have extremely good precision (uniform diameter) but have incredibly bad accuracy and break a collet.
 
A digital caliper may be accurate to 0.001 " but I defy anyone to get repeatable readings of that precision. If you are going to make your own collets and chucks then micrometer readings will be better and a plug gauge for internals.

No question on the superiority of micrometer readings, as I hope was clear above. But I have to say that my own experience suggests that repeatable readings with an accuracy of +/- .001 are indeed possible using a digital caliper. It does take practice and a careful "feel" for the tool. Probably there are some old-timers who can reliably take such a reading in a single try, but I always test any reading with another - or to say it another way, I never trust a caliper reading unless I CAN repeat it, every time I take it.

The exception would be a depth reading - while the versatility of a digital caliper does allow taking a depth reading, the "base" one uses in the process is so small / instable that variations of +/- .010 or more are the norm, at least for me. Again, probably someone with more experience can do better.
 
FWIW,

I made an ER-11 collet adapter following Arnold's original post a few years ago. It is not a hard project to accomplish. I bought a collet nut and some collets from a supplier (Travers) and everything worked well to solve the problem I had at the time. I have since bought an ER-25 package of collet adapter and collets sold for my Mini-lathe by LMS. All of these things are not the high-end products, but do the job I need them to do.

If you can afford the best, buy it; otherwise you have to balance your need against your budget for money and the time you want to spend making tooling.

--ShopShoe

P.S.: Even inexpensive micrometers offer more precision than calipers: They will increase your precision when you use them.

--SS
 
Just a small comment on the use of silversteel: we do not use it any longer in our local horology club. We found the Swiss made ETG100 steel superior in ease of cutting and quality of finish. It can be hardened the same way and hardness as silversteel. We use it for shafts, pinions and gearcutters, and for the occasional off-size collet.
 
With regards to holding long lengths in a collet Smart & Brown lathes used a system that had a tubular draw bar to close the collet via a hand wheel on the end of it, I seem to remember it having about a 1" bore but I don't recall the taper. (it was 50 years ago).
 
What does this (With regards to holding long lengths in a collet Smart & Brown lathes used a system that had a tubular draw bar to close the collet via a hand wheel on the end of it, I seem to remember it having about a 1" bore but I don't recall the taper. (it was 50 years ago) have to do with no pictures?
 
My comment refers to the original subject of collets and the desire to be able to hold long lengths of bar if the thread had been followed this would be apparent. It is common for post to wander a bit and then come back to the original main topic.
 
Do you recommend a particular brand of micrometer? Has anyone got experience using Insize products for example? I've seen that they make go no go gauges as well as micrometers.
 
If you earn a living from machining, you'll want to get something like a Mitutoyo - which will not be cheap, but should last you forever if cared for. If you are a hobby machinist, you may be satisfied with an import - take your pick on brands.

Note several things regardless of the brand:

The accuracy and precision (repeatability) of your readings will depend on developing a "feel" - it is possible to change the reading by half-a-thou by how firmly you turn it to the measurement. Two systems are used to try to give consistency of "feel" - a "friction" style and a "ratchet" style. There will be proponents of each - take your pick, and learn to use it against a standard so that you can get accurate and repeatable results.

But with regard to the standard, the second thing to know is that micrometers are adjustable. Generally there is a set screw (maybe under a cap) or some other mechanism to lock the barrel to the spindle. Once you have a consistent "feel" for how you use the micrometer, measure a standard, and if it is off, unlock the barrel, rotate to the correct reading, and lock it back. From time to time, check the micrometer against a standard to make sure it is still set correctly.

Finally, note that any debris, even tiny, can throw off the measurement. Make sure the part is clean, and make sure the ends of the spindle are clean as well.
 
Last edited:
Do you recommend a particular brand of micrometer? Has anyone got experience using Insize products for example? I've seen that they make go no go gauges as well as micrometers.
I have a few insize digital gauges, they work well, except they will chew thru batteries even when turned off. Alkaline cells have a steep voltage curve. Silver oxide cells will last longer as they maintain voltage better and you must use them with Mitutoyo. I have two Mitutoyo digital calipers one 15 years old and the other 10 and they still work perfectly.
 
I can't really afford a Mitutoyo or Mahr, although the Mahr 'digital wireless output' feature looks interesting. It looks like it feeds the dimensions into the computer using a little USB? I think I'm going to get vernier calipers. They seem to be more middle of the range for hobby machinists.
 
Going back to 1968 Mitutoyo came into the UK and were treated with great skepticism, but as they were a third of the price of all the known brands were very popular with apprentices and quickly became the tool of choice, they were also the first to have carbide anvils on the mics, so basically would probably out live the user. In the 80,s premium brands of model aircraft engines O.S etc were copied by the Chinese and were not regarded as reliable but! were half the price and gained a following
and are now generally very good. Look how many generators garden tools etc have Honda clones and most of us don't give it a second thought. Soon Chinese imports will be the norm I'm sad to say. We live in a disposable society where the majority have to consider cost.
 
chew thru batteries even when turned off.
Thanks for letting me know!
I've also been advised to look for IP67 which means it can be submerged in 1m of water for 30 minutes. I would have thought that they would all have this? Or does this rating refer to their measuring performance rather than corrosion resistance?
 
I can't really afford a Mitutoyo or Mahr, although the Mahr 'digital wireless output' feature looks interesting. It looks like it feeds the dimensions into the computer using a little USB? I think I'm going to get vernier calipers. They seem to be more middle of the range for hobby machinists.

You will never get as accurate a reading with a vernier compared to a micrometer, digital or not.
My first engines were built using a 30 year old Moore &Wright micrometer with the ratchet mechanism missing so feel was all I had to go by.
Micrometer can also be affected by temperature, hence the usual finger and thumb holding pattern while taking readings.
 
Going back to 1968 Mitutoyo came into the UK and were treated with great skepticism, but as they were a third of the price of all the known brands were very popular with apprentices and quickly became the tool of choice, they were also the first to have carbide anvils on the mics, so basically would probably out live the user. In the 80,s premium brands of model aircraft engines O.S etc were copied by the Chinese and were not regarded as reliable but! were half the price and gained a following
and are now generally very good. Look how many generators garden tools etc have Honda clones and most of us don't give it a second thought. Soon Chinese imports will be the norm I'm sad to say. We live in a disposable society where the majority have to consider cost.

Your correct about the reliability of generators, lawn movers etc with Honda engines but Honda is a Japanese Company not Chinese.
 
I have found the cheaper brands of inside telescopic caliper to be no where near as good as the Moore&Wright or similar.
Difference being the cheaper brand have both ends floating whereas the latter above has only one end spring loaded.
Result is a better feel and therefore more accurate when transferred to an open mic.
Use the double ball inside caliper for smaller holes and again Moore&Wright.
 
ok thanks guys, I'll look into micrometers rather than calipers. I've read that you are supposed to wipe micrometers with a cloth before you put it away to remove the oil, water and dust? Is this true and if so, are there any that are more resilient?
 

Latest posts

Back
Top