Hey Carl,

Thank you for your responsiveness and information-packed posts. ?If we were serving in the Navy, I'd offer you a Bravo Zulu.?

Yup, clean, consistent setups. I did check runout at every point you mentioned, including the mounting face of the spindle. ?

CLA: Clean, lubricate & adjust. ?Compaq is a highend Swiss brand of test indicator. And tough, too.

How I measured runout (in the tapered bore): ?I setup up the indicator per manufacturer's instructions. ?I indicated, rotationally, on a point near the smallest diameter of the chuck's taper. ?All good until I got to the point on the diameter that threw a .004" wow. ?I marked this point on the outside of the chuck. ?Made several indications at points of increasing diameter until I reached a point close to the widest diameter of the taper. All with the same results/same point on the diameter of the cone.

Then I broke the setup down, cleaned/inspected again, and repeated. Same results/same part of the taper.

I also indicated several pieces of different diameter ground silver steel rod mounted in the chuck. Same results, same part of the taper. ?I opened the chuck, rotated the collets 180 degrees (maintaining work piece position), and measured again. ?After that, I did the same with a 90 degree rotation. ?Same .004" runout along the position marked on the chuck.?

About grinding: ?I have a new dremel tool with a bunch of stone points. ?Also a recently acquired a QCTP set from the eBay seller in Central CA. ?The dremel tool holder is extremely well made, and fits nicely on any threaded Dremel tool I've tried . ?I'm not sure about which of the dremel stones/grit to use for this operation, or which of the thousands of available grinding points are cost effective for this job. ?This is one of those jobs that I set aside 3-4 months ago, and am just now reconsidering.

I did try your suggestion on setting up the Unimat for taper turning, using the original part as a guide to indicate off of. ?It's easy, and only took a couple of minutes to achieve sub-.0005" runout. ?

Thanks again for your great observations and timely suggestions.

Best,

James

On Thursday, March 19, 2020, 11:08:23 AM PDT, Tamra <tamrabrogdon@...> wrote:

Thanks Carl, I read the explanation, but I don't know how to implement.
Ok... I want a class.? who wants a visit from a hobby machinist on their doorstep?

I would really love to be able to set up a bunch of measuring devices.

<Good Grief>? the neighboring city has stopped all non-essential travel 6 minutes ago, so need a YouTube video!? I can't drive west.

I wish I could shrink myself and go to work with some of you.

Tamra

On Thursday, March 19, 2020, 6:51 AM, Carl <carl.blum@...> wrote:

Hi Gang:

The runout is something that can be fixed. Most lathe chucks come with a mounting plate that you machine on your lathe.?

I would inspect first your lathe's spindle to make sure it runs true and has no burrs. Then check the bore and mounting face of the collet holder. Install the holder on the spindle with the nut out and no collet. This should be a smooth and easy assembly. If anything binds check again for burrs. Then use your indicator to check the tapered bore for runout.?

If there is too much runout, mark the holder in quarters. Make a note of where the indicator reads high and carefully use a sharpening stone to reduce that side of the mounting space. Be aware that a 0.001" removed from the face will change the runout 0.002" so be gentle. I like to coat the face I'm "stoning" with magic marker so I can watch as I remove the material. Repeat the process until you are happy with the results. Also know that you can't get a runout better than the spindle. This is how I corrected the ER-32 collet holder I made for my Unimat.

Actually a 0.004" runout isn't too bad for a first install. Just 0.002" off the face should fix it.

Good luck, Carl.

Hi Carl,
Your post raised some questions for me, and I thought I'd start a new thread rather than hi-jack Heather's original...

So...I did all of the basic wipe it down/inspect it machinist stuff before mounting the collet chuck. ?And started using using the setup to machine 1/8" brass rod and 1/4" mild steel. ?None of what I was doing required any serious level of precision...but as I was making each part, I could clearly see that I had a runout problem along every surface/profile I was cutting.?

So...I took the chuck off, and cleaned every thing again, checked the Unimat spindle shaft & face for runout using a recently CLA'd and calibrated Compaq . ?The Unimat was still under .0005" runout.

The problem was the RC Machines collect chuck. ?The tapered bore has a .004" ditch that runs axially along the same point along the diameter. ?That is, a straight line that starts at the skinny end of the taper and ends at the fat end. ?The runout translates directly to every piece turned, or held in the collet/chuck fixture. ?For the newer than me machinist reading this, this means that every thing you turn using this fixture will have a .004" high wobble that tapers along the length.

So what to do about it? ?

You mentioned stoning the ER chuck's tapered bore. ?I've never done that. ?Could you explain that process a little more? ?Or point to a source that you think does effectively illustrates what you're talking about?

I was considering either boring or grinding to correct this, but I don't have any experience with precision tapers or grinding so I've set this aside until I find an approach that I feel comfortable with. ?Of course, now that I'm stuck in camp Covid along with the rest of the world, I've got more time on my hands to try and figure it out.

Anyone else out there have any suggestions?

Cheers,
James

?

Carl and group... sorry to ask, with kindness...but I need a picture with some arrows???

I think I would be much, much, happier with an ER-32 spindle, but don't know how to adjust it to fix the runout issues.

I do understand the .002 adjustment, but .004 with a pair of dial calipers seems so inaccurate to me when I am measuring my results.

Tamra

On Mar 19, 2020, at 02:40, Andy Carlson <andycarlson@...> wrote:

?

I would back up the recommendations to set yourself up with an ER16 collet system. I have one on my Unimat SL and I use it a lot.

?

I have the ER16 collets from Arc Euro Trade and have found these good and not too pricey. Others have bought cheaper ‘no name’ collets from eBay and have found more variable results. The Arc ones can be bought as a set. There are more than ten in a set because the smaller sizes go up in half millimetre increments.

?

Arc also do a collet holder but this needs to be mounted on a separate backplate. This is what I have but I can’t recommend this product for someone who is learning because the backplate requires machining before it can be used.

?

I’ve found that offcuts of extruded aluminium strip/angle seem to mill OK but otherwise I’d back up the advice to steer clear of ‘repurposed’ unknown metals or buying low grade bar/strip etc from the DIY sheds.

?

Regards, Andy

?

From: [email protected] [mailto:[email protected]] On Behalf Of Alfred Fickensher
Sent: 19 March 2020 02:34
To: [email protected]
Subject: Re: [Unimat] Milling and collets

?

Heather, etal, a year ago I bought this one. I then bought a set of 1-10 metric and a set of 1/32 - 3/8 inch Chinese collets for it. As a novice I have found it does everything I've wanted it to do so far. I've even chucked up a collet in it and used it as a very handy hand vise for some file shaping of a brass rod for a model rr detail part.

?

I had and still have ill feelings about their customer relations attitude and payment policies but then I'm just a one-time customer and a small-purchase one at that. There might well be some cultural differences as well that I didn't recognize. Regardless of how I feel about them as a business, I can recommend their collet holder for the Unimat SL.

?

<<>>

?

alf,

On Mar 18, 2020, at 21:09, Keith S. Angus via Groups.Io <ksangus@...> wrote:

?On Wed, Mar 18, 2020 at 05:57 PM, <hcamalcolm@...> wrote:

Which Collets should I buy??

which milling cutters should I buy??

what’s a good source of offcuts if aluminium and brass that I can practice on??

Welcome Heather,

My recommendation is to use ER16 collets. Cheap but accurate ones can be had from China. Getting holders for them is more difficult. It's the luck of the draw whether you can find a decent one on sale, but it leads back to the question of which Unimat do you have, and what accessories came with it? If you're not sure what you've got, or even what the bits are called, look at the instructions in the Files section, They will also give you an idea of what sort of work you can do with these machines. For milling cutters don't go bigger than 6 mm (1/4"). Cutters can go down to really small - I've seen 0.2 mm diameter but I've never dared to try one. I suggest an assortment around 3, 4, 5 mm, and with 2, 3, or 4 flutes will suit a range of jobs.

As for metals I suggest, as one example, Noggin End Metals (? ? ). They have the advantage that they know what grades they are selling, including the ones listed below:

For steel use EN1A, which is a free cutting grade. It cuts easy and will do for most things until you need to be really fussy about strength or finish. There is a huge range of steels and some of them are a nightmare to machine. EN1A is specifically formulated for easy machining.

For brass you want CZ121, which is a hard brass and is generally reckoned to be the easiest material to machine. Like steels, there are many grades of brass, but CZ121 is the most free machining.

For aluminium 6082 (also known as HE30) is a good grade. It machines cleanly. As you may have guessed by now there are innumerable grades of aluminium alloys, but many of them are soft and clog up the cutters.

The best machining plastic is acetal (also known as Delrin). It machines cleanly and has the look and feel of Nylon (which is a pain to machine but cheaper). It is low friction and difficult to glue. You may want to machine acrylic (Perspex) and it's not too bad, but you need very sharp cutters and gentle cuts to avoid it overheating. Acrylic is unlike almost all other plastics when it comes to machining. Plastics are broadly grouped as Hard, Soft & Acrylic when it comes to machining - acrylic is just different!

All this applies to milling and turning. What are you hoping to make?

You will have lots of questions to start with - just ask - like we all had to when we started out.


Keith

Hi Heather, what are you going to make?? I pretend to make scale miniatures - generally working in 1/12th scale.... I generally work in brass on my unimat...

Welcome to the group!

I chased down the WW Spindle, and actually found one in my state at an antique store. (I just had to have one!) Since it was kinda expensive, I wanted to see it in person before the purchase, it was about 100+ miles from home, but getting collets for the WW Spindle is another story... so purchasing an option manufactured today is a less frustrating option.? I was told not to do this, but had to have the WW Spindle.

I don't think I would be happy with .004 runout, I would always be questioning if it is the equipment or me?? ?The downside of learning what precision machining is, is that after you get to a certain skill level, you want it to be precise!

Tamra

Hi all,

I’ve also dealt, once, with RC Machines. The ER16 collet chuck came with .004” runout. No response from customer service. Only a $90-$100 tool, so I’m not out much. But I won’t do business with them ever again.

Great advice about materials and cutting tools. Heather, that’ll save you a lot of time along the learning curve.

On Wednesday, March 18, 2020, 7:33 PM, Alfred Fickensher <alfickjr@...> wrote:

Heather, etal, a year ago I bought this one. I then bought a set of 1-10 metric and a set of 1/32 - 3/8 inch Chinese collets for it. As a novice I have found it does everything I've wanted it to do so far. I've even chucked up a collet in it and used it as a very handy hand vise for some file shaping of a brass rod for a model rr detail part.

I had and still have ill feelings about their customer relations attitude and payment policies but then I'm just a one-time customer and a small-purchase one at that. There might well be some cultural differences as well that I didn't recognize. Regardless of how I feel about them as a business, I can recommend their collet holder for the Unimat SL.

<<>>

alf,

On Mar 18, 2020, at 21:09, Keith S. Angus via Groups.Io <ksangus@...> wrote:

?On Wed, Mar 18, 2020 at 05:57 PM, <hcamalcolm@...> wrote:

Which Collets should I buy??

which milling cutters should I buy??

what’s a good source of offcuts if aluminium and brass that I can practice on??

Welcome Heather,

My recommendation is to use ER16 collets. Cheap but accurate ones can be had from China. Getting holders for them is more difficult. It's the luck of the draw whether you can find a decent one on sale, but it leads back to the question of which Unimat do you have, and what accessories came with it? If you're not sure what you've got, or even what the bits are called, look at the instructions in the Files section, They will also give you an idea of what sort of work you can do with these machines. For milling cutters don't go bigger than 6 mm (1/4"). Cutters can go down to really small - I've seen 0.2 mm diameter but I've never dared to try one. I suggest an assortment around 3, 4, 5 mm, and with 2, 3, or 4 flutes will suit a range of jobs.

As for metals I suggest, as one example, Noggin End Metals (? ? ). They have the advantage that they know what grades they are selling, including the ones listed below:

For steel use EN1A, which is a free cutting grade. It cuts easy and will do for most things until you need to be really fussy about strength or finish. There is a huge range of steels and some of them are a nightmare to machine. EN1A is specifically formulated for easy machining.

For brass you want CZ121, which is a hard brass and is generally reckoned to be the easiest material to machine. Like steels, there are many grades of brass, but CZ121 is the most free machining.

For aluminium 6082 (also known as HE30) is a good grade. It machines cleanly. As you may have guessed by now there are innumerable grades of aluminium alloys, but many of them are soft and clog up the cutters.

The best machining plastic is acetal (also known as Delrin). It machines cleanly and has the look and feel of Nylon (which is a pain to machine but cheaper). It is low friction and difficult to glue. You may want to machine acrylic (Perspex) and it's not too bad, but you need very sharp cutters and gentle cuts to avoid it overheating. Acrylic is unlike almost all other plastics when it comes to machining. Plastics are broadly grouped as Hard, Soft & Acrylic when it comes to machining - acrylic is just different!

All this applies to milling and turning. What are you hoping to make?

You will have lots of questions to start with - just ask - like we all had to when we started out.


Keith

On 19 Mar 2020, at 02:09, ksangus via [] <ksangus=btopenworld.com@[]> wrote:

?On Wed, Mar 18, 2020 at 05:57 PM, <hcamalcolm@...> wrote:

Which Collets should I buy??

which milling cutters should I buy??

what’s a good source of offcuts if aluminium and brass that I can practice on??

Welcome Heather,

My recommendation is to use ER16 collets. Cheap but accurate ones can be had from China. Getting holders for them is more difficult. It's the luck of the draw whether you can find a decent one on sale, but it leads back to the question of which Unimat do you have, and what accessories came with it? If you're not sure what you've got, or even what the bits are called, look at the instructions in the Files section, They will also give you an idea of what sort of work you can do with these machines. For milling cutters don't go bigger than 6 mm (1/4"). Cutters can go down to really small - I've seen 0.2 mm diameter but I've never dared to try one. I suggest an assortment around 3, 4, 5 mm, and with 2, 3, or 4 flutes will suit a range of jobs.

As for metals I suggest, as one example, Noggin End Metals (? https://www.nogginend.com/? ). They have the advantage that they know what grades they are selling, including the ones listed below:

For steel use EN1A, which is a free cutting grade. It cuts easy and will do for most things until you need to be really fussy about strength or finish. There is a huge range of steels and some of them are a nightmare to machine. EN1A is specifically formulated for easy machining.

For brass you want CZ121, which is a hard brass and is generally reckoned to be the easiest material to machine. Like steels, there are many grades of brass, but CZ121 is the most free machining.

For aluminium 6082 (also known as HE30) is a good grade. It machines cleanly. As you may have guessed by now there are innumerable grades of aluminium alloys, but many of them are soft and clog up the cutters.

The best machining plastic is acetal (also known as Delrin). It machines cleanly and has the look and feel of Nylon (which is a pain to machine but cheaper). It is low friction and difficult to glue. You may want to machine acrylic (Perspex) and it's not too bad, but you need very sharp cutters and gentle cuts to avoid it overheating. Acrylic is unlike almost all other plastics when it comes to machining. Plastics are broadly grouped as Hard, Soft & Acrylic when it comes to machining - acrylic is just different!

All this applies to milling and turning. What are you hoping to make?

You will have lots of questions to start with - just ask - like we all had to when we started out.


Keith

Heather, etal, a year ago I bought this one. I then bought a set of 1-10 metric and a set of 1/32 - 3/8 inch Chinese collets for it. As a novice I have found it does everything I've wanted it to do so far. I've even chucked up a collet in it and used it as a very handy hand vise for some file shaping of a brass rod for a model rr detail part.

I had and still have ill feelings about their customer relations attitude and payment policies but then I'm just a one-time customer and a small-purchase one at that. There might well be some cultural differences as well that I didn't recognize. Regardless of how I feel about them as a business, I can recommend their collet holder for the Unimat SL.

<<>>

alf,

On Mar 18, 2020, at 21:09, Keith S. Angus via Groups.Io <ksangus@...> wrote:

?On Wed, Mar 18, 2020 at 05:57 PM, <hcamalcolm@...> wrote:

Which Collets should I buy??

which milling cutters should I buy??

what’s a good source of offcuts if aluminium and brass that I can practice on??

Welcome Heather,

My recommendation is to use ER16 collets. Cheap but accurate ones can be had from China. Getting holders for them is more difficult. It's the luck of the draw whether you can find a decent one on sale, but it leads back to the question of which Unimat do you have, and what accessories came with it? If you're not sure what you've got, or even what the bits are called, look at the instructions in the Files section, They will also give you an idea of what sort of work you can do with these machines. For milling cutters don't go bigger than 6 mm (1/4"). Cutters can go down to really small - I've seen 0.2 mm diameter but I've never dared to try one. I suggest an assortment around 3, 4, 5 mm, and with 2, 3, or 4 flutes will suit a range of jobs.

As for metals I suggest, as one example, Noggin End Metals (? https://www.nogginend.com/? ). They have the advantage that they know what grades they are selling, including the ones listed below:

For steel use EN1A, which is a free cutting grade. It cuts easy and will do for most things until you need to be really fussy about strength or finish. There is a huge range of steels and some of them are a nightmare to machine. EN1A is specifically formulated for easy machining.

For brass you want CZ121, which is a hard brass and is generally reckoned to be the easiest material to machine. Like steels, there are many grades of brass, but CZ121 is the most free machining.

For aluminium 6082 (also known as HE30) is a good grade. It machines cleanly. As you may have guessed by now there are innumerable grades of aluminium alloys, but many of them are soft and clog up the cutters.

The best machining plastic is acetal (also known as Delrin). It machines cleanly and has the look and feel of Nylon (which is a pain to machine but cheaper). It is low friction and difficult to glue. You may want to machine acrylic (Perspex) and it's not too bad, but you need very sharp cutters and gentle cuts to avoid it overheating. Acrylic is unlike almost all other plastics when it comes to machining. Plastics are broadly grouped as Hard, Soft & Acrylic when it comes to machining - acrylic is just different!

All this applies to milling and turning. What are you hoping to make?

You will have lots of questions to start with - just ask - like we all had to when we started out.


Keith

?

Heather, etal, a year ago I bought this one. I then bought a set of 1-10 metric and a set of 1/32 - 3/8 inch Chinese collets for it. As a novice I have found it does everything I've wanted it to do so far. I've even chucked up a collet in it and used it as a very handy hand vise for some file shaping of a brass rod for a model rr detail part.