First Major DRO Job

[gerritv]

No spot drilling??? Don't you worry about tip wander?

stub drills, 135dg, most are split point. All adds up to little or no wander on a flat surface. I just lightly touch first to make a tiny spot, then go in.

 

[jcdammeyer]

Mine does things like bolt circles but I have to pull out the manual each time to figure out how to use it.
Connects to the cheap (likely no longer available) Chinese scales. Also works with a probe (and probe diameter) to find the center of a hole.

I downloaded that Android DRO app onto my Samsung Tablet. Nice. If one can find a used tablet for $50 or so then this might be an inexpensive way to go.

DIY DRO Project

Blog dedicated to DIY digital readout TouchDRO and other hobby machining and engineering subjects.

www.yuriystoys.com

For fun I've ordered a couple of these BlueTooth Modules.

2.71C$ 8% OFF|New Version Hc-06 Hc 06 Rf Wireless Bluetooth Transceiver Slave Module Rs232 / Ttl To Uart Converter And Adapter - Integrated Circuits - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

 

[Susquatch]

look forward to a picture of this whole contraption your building mounted

All done!

I have another job on the lathe right now so mounting it will have to wait!

 

[Susquatch]

I would just get a 7mm ER32 collet. Very common. 17/64th —> ~ 6.75 mm; it will never fit a 1/4” collet as that would have to “stretch” - which ERs don’t.

Ive tried in vain to make sense of this @RobinHood .

I can find references to both metric and Imperial ER Collets, but when I dig into the details I either find that they are actually the same or I find nothing definitive.

Here is a sample chart from Little Machine Shop.

Here is a link if you want more detail.

ER Collet Sizes

This page shows the size and clamping range of the various size ER collets that we carry.

littlemachineshop.com

Notice that a 3/16 collet is also listed as a 4 to 5 mm collet. This is true through the full range.

Other web sites don't necessarily list them this way. Most list a set of separate metric collets or an imperial set. I cannot find such as set that provides actual dimensional information to prove that they are really either metric or imperial.

This leaves a rather difficult set of alternatives. Either both are actually the same just different labels, or they are physically different with different dimensions.

Rego (the inventor of RE Collets) sells both Metric and Imperial collets, but they don't have a 7mm. Just 6 & 8. They don't provide detailed dimensions. It would be interesting to check to see if a 1/4" drill or end mill will fit into their 6mm collet. That might tell us if the markings were truly metric or just a marketing plot to sell more collets.

I happen to have an imperial set. I don't really want to buy a metric set and then discover that they are really the same.

Do you (or anyone else) have a metric set that they can actually measure?

If not, I will try to buy ONE metric collet and see what happens.

 

[gerritv]

I have several metric collets (5C, ER16, ER20) In ER16/ER20 I have a 'full' set of 1mm increments. I also have imperial sizes for shanks that I use often, specifically 1/8, 1/4 and 5/16.
A 1/4" bit will/should not fit in a 6mm collet. If you force it in, you ruin the collet, it is now sprung. 6mm is 0.236" Collets grip best at their nominal size. So while a 6-5mm collet can ostensibly be used at 5mm, it takes a lot of force to close, and the likelyhood of runout is higher.

My advice is to buy a set, and then for the other style (as in imperial or metric) buy nominal sizes for the shanks you use.

A pin of nominal size slides smoothly into a properly sized collet. So my 1/8" shop made engraving bits fit great in the 1/8 collet. It won't fit in a 3mm collet, but will in a 3-4 but lots of closing down, with runout as a result.
When it matters, as in I want minimal runout, I buy specific sizes, with no clamping range. An example (I haven't bought from them but is shows what is available) https://www.aliexpress.com/item/1005001516713169.html . And when I am flush with money, I go for the AA grade. The smaller the cutter, the more runout matters, es. with carbide. Since I am heading into the sub mm world over the next while I am starting to pay attention to these details
Gerrit

 

[gerritv]

For clarification, By full set I mean of course the sets marked with ranges such as 3-4mm.

 

[PeterT]

IMP & MET collets are not the same. I think this is a case where LMS is trying to be helpful by converting, unfortunately is causing potential confusion as it pertains to physical sizing. They do that elsewhere on the site, maybe its hole/thread sizing I cant recall. Anyways you don't want to stretch collets above nominal even if it appears dimensionally close. And collets do have a recommended squeeze range (diameter reduction) but that varies by collet type. The ramifications are worth considering. Distorting (ruining) a collet is one thing. Having it come lose when you thought it was tight can pooch up some milling work you may have invested time & cost.

 

[DPittman]

And collets do have a recommended squeeze range (diameter reduction) but that varies by collet type.

I agree and it makes sense that a collet should not be stretched at all. I have OZ25 collets and I have never been able to find the recommended squeeze range for them but I use 1/64" as that is what I saw for other er collets I believe.

 

[Susquatch]

@gerritv @PeterT - I am aware that the collets can't be expanded - only tightened, and that they can accomodate a range. But I appreciate your input anyway. You don't know what I know or what I don't know - so better safe than sorry.

I want to believe that you are right that metric collets really are metric, and that Imperial Collets really are Imperial. But the more I look the more I find evidence to the contrary. It makes me nervous.

For example, I looked a little closer at the little machine shop collets. Contrary to my first assumption, it turns out that they are actually metric with Imperial markings. Not imperial with metric. Go figure!

Believe it or not, I actually think getting a true metric collet is more likely on Ali just because they are much more likely to make the mistake (if it is a mistake. Wierd trying to think like them. LOL)

My take away from this little exercise is: If you are buying ER Collets, make sure you are really getting what you think you are getting, or at least make sure that you will be happy either way - which is of course entirely possible.

I'm actually finished the job that I needed a metric 7mm collet for. Since it was in range and since it just felt bad but was really ok, I just ignored my concerns and cranked the collet down. So there is no rush anymore at all.

Right now, my plan is to buy a few selected metric collets (only as required) from someplace like Amazon or my local jobber so they can be returned if they are not really the true metric ones I want.

 

[DPittman]

@gerritv @PeterT - I am aware that the collets can't be expanded - only tightened, and that they can accomodate a range. But I appreciate your input anyway. You don't know what I know or what I don't know - so better safe than sorry.

I want to believe that you are right that metric collets really are metric, and that Imperial Collets really are Imperial. But the more I look the more I find evidence to the contrary. It makes me nervous.

For example, I looked a little closer at the little machine shop collets. Contrary to my first assumption, it turns out that they are actually metric with Imperial markings. Not imperial with metric. Go figure!

Believe it or not, I actually think getting a true metric collet is more likely on Ali just because they are much more likely to make the mistake (if it is a mistake. Wierd trying to think like them. LOL)

My take away from this little exercise is: If you are buying ER Collets, make sure you are really getting what you think you are getting, or at least make sure that you will be happy either way - which is of course entirely possible.

I'm actually finished the job that I needed a metric 7mm collet for. Since it was in range and since it just felt bad but was really ok, I just ignored my concerns and cranked the collet down. So there is no rush anymore at all.

Right now, my plan is to buy a few selected metric collets (only as required) from someplace like Amazon or my local jobber so they can be returned if they are not really the true metric ones I want.

My OZ25 collets are easy and cheap to find in metric, not so much in imperial but I do have a set of 10 ranging from 1/8" to 1"

 

[gerritv]

@Susquatch you are over thinking this.
A more reputable source of info, Haimer. They list metric and imperial collets. If you do the conversion, a 2-3mm collet has a max opening of 3mm or 0.118" , a 1/8" collet has a max opening of .125". A 3-4mm collet would have a max opening of .157" so a 3mm shank would fit but again, not optimal. Within the ranges as presented on LMS their reco works, but not best practice for holding power. Advice found elsewhere "Choosing a collet that exactly matches the cutting tool diameter improves grip force, accuracy, and rigidity, resulting in extended tool life and better surface finishes."
If/when you buy the LMS ones, you will be buying from Asia so personally I just go there in the first place and save my $. I have had 0, nada issues with quality of er11/16/20/32 collets. When I order an AA precision one, that is what I get. (and yes, I can measure to 5 microns) My first ER11 set was very inexpensive, and it still has acceptable runout. Proper tightening helps with that as well.

gerrit

 

[PeterT]

I looked a little closer at the little machine shop collets. Contrary to my first assumption, it turns out that they are actually metric with Imperial markings. Not imperial with metric. Go figure!

Hmmm... that sounds a bit cheesy IMO. Every tooling catalog I've ever seen makes a clear distinction between Imperial & Metric. Again, not sure if LMS is trying to be helpful, but I think it adds to confusion. I mean lets go all in & call a metric drill set 'fractional', a 3mm is actually 7.56/64"!

 

[gerritv]

Its worse in the catalog photos, the markings are imperial. And then in the text they claim equivalent metric sizes. Which is not possible at nominal. The AliExpress store(s) I bought/buy mine from do not make that mistake. If I order imperial 1/8" that is what I get, and marked as such.

Gerrit

 

[PeterT]

I actually think getting a true metric collet is more likely on Ali just because they are much more likely to make the mistake (if it is a mistake. Wierd trying to think like them

I think the likelihood of metric is more likely because Ali (and large part of manufacturing world) is predominantly metric when it comes to tooling at least, unless they think there is a market for imperial. They do the same thing btw, list things as IMP. I assume to be helpful. But for every Imperial tap or end mill on Ali, you'll see 1000 metric

 

[gerritv]

@PeterT As my just prior post says, I order imp, I get imp from AliExpress and similarly with metric. They actually know the difference. I have bought both so have experience with it..

 

[DPittman]

I have bought the majority of my metric collets from Aliexpress and only the odd imperial one as they're hard to find in my style. There has been a difference in quality of the collets however, some were just not as nicely finished of (burrs on inside slits mainly) but I did have one metric one that was such a hard and poor fit into the chuck nut I threw the dang thing away. Unfortunately I have no idea which supplier was the bad one as I ordered here and there, waited for months for them to arrive and then by the time I went to use it, I had no recollection of whom I purchased it from.

 

[jcdammeyer]

I bought a set of ER32 Metric AA collets from China. Wasn't cheap but they appear to be good quality. As a test just now I took a 1/4" drill bit (6.35mm) and mounted the 7-6 collet into the square collet block. The numbering seems consistent in that the largest opening is 7mm and it can compress down to 6mm. In this case it went down to 6.35 smoothly. The next smaller collet is 6-5 so it push came to shove and I had an exact 6mm diameter shaft I'd use the 6-5. The 6.35 drill bit does not fit in the 6-5. (I suppose it could be forced but why?)

Then after I tightened it I used some narrow feeler gauges to see if the collet slots were angled at all. In the area below the drill bit the gap in each of the slots was about 0.001" to 0.002" smaller. However from the top for the length of the drill bit shank the spacing was consistent all the way around. It didn't get any smaller so the compression appeared to be fairly even.

As best as I could measure.

 

[Susquatch]

I actually think getting a true metric collet is more likely on Ali just because they are much more likely to make the mistake (if it is a mistake. Wierd trying to think like them

I think the likelihood of metric is more likely because Ali (and large part of manufacturing world) is predominantly metric when it comes to tooling at least, unless they think there is a market for imperial. They do the same thing btw, list things as IMP. I assume to be helpful. But for every Imperial tap or end mill on Ali, you'll see 1000 metric

Yes, that was my point. Being in China, metric is the goto standard. Hence stuff like M1/4 LOL!

But I started this part of the thread back when I first encountered the confusion on the Rego website. Since Rego is the inventor of the ER Collet, I gave their information the highest credibility. I see now that this was a mistake. Their marketing guys must have been hard at work making a mess of things.

@Susquatch you are over thinking this.
A more reputable source of info, Haimer. They list metric and imperial collets. If you do the conversion, a 2-3mm collet has a max opening of 3mm or 0.118" , a 1/8" collet has a max opening of .125". A 3-4mm collet would have a max opening of .157" so a 3mm shank would fit but again, not optimal. Within the ranges as presented on LMS their reco works, but not best practice for holding power.

I freely confess that I usually overthink things. That is just how I am wired. Whenever I encounter things that don't make sense, I usually assume somebody made an honest mistake. But I also consider the possibility that I might not know something. So, I dig a bit deeper. (overthink) I usually start that process by getting more info from the most credible source of info I can find - in this case Rego.

Now that the dust has settled, I know that there really are both true metric and true imperial ER Collets. Frankly, other than for improved nominal fit, I don't really see the point of this. Since collets are designed to fit a range of sizes anyway, metric only would have been just fine - especially since 1mm (0.0394) is a finer increment than 1/16 (0.0625)

I also dove a bit deeper into the LMS chart and I believe you are correct. They are just trying to be helpful. Basically, they are saying that you can use a 6-7mm collet to hold a nominal 1/4" shaft. If they had put metric first in their chart and then titled the imperial column as "Also fits Imperial" and moved that column further right without the bolding, it would have been ok. Especially since that is almost exactly what I was trying to accomplish in the first place! I was trying to find a better fitting collet for a 17/64 drill. As you all know, collets don't expand. So a 17/64 drill requires a 5/16 collet and won't fit a 1/4" collet. But, tightening a 5/16 collet down to 17/64 hurt my sensibilities - WAY TOO MUCH tightening. A 7mm collet would have been better. Hence my over thought journey.

Anyway, my previous closing advice still stands. When shopping for ER collets, be careful. There is some misleading info out there and it would be disappointing to get the wrong collet.

 

[gerritv]

The Rego info is quite clear to me Is it becasue I am born in EU? Not sure.
This screen shot shows the entry for an 8.5mm ER16 collet. Normal size is 8.5mm/0.33" and it has a range, metric and imp. But the nominal size is 8.5mm regarldess of what else you can fit in it. The best grip will be on that nominal size, anything else will be less. That is the whole point of using nominal sizes, just like with 5C collets (which have almost no gripping range outside the nominal). The same info for a 7/32" collet shows it is nominal 7/32, with a metric equivalent shown.

 

[Susquatch]

There has been a difference in quality of the collets however, some were just not as nicely finished of (burrs on inside slits mainly)

I've had a few like this too. I bought a very cheap ER11 set for my Spindle Motor Based Tool Post Grinder. They work well enough for that but they were crammed with burrs.