end mill holder accuracy

Quality has to be assessed on an item by item basis, you can no make generalizations based on brand or country of origin. The drill chuck with R8 shank that came with my Harbor Freight mini mill (Seig X2) is great and compares well with another Yuasa one I have.

I have yet to see marketing folks try to be clever and say stuff like

"we moved production to China to increase quality. QC staff are cheaper there and you get better products at a better price".

This A2Z atuff is alleged to be made in the USA, but is junk. It's possible Prison Factory #44 would do a better job.

In this examle they might want to consider offshoring.

If you can come up with examples if stuff moving to china and the quality going up, they'd be fun to hear.

My only anecdote is ThinkPad laptops from IBM. They went from US to Mexico and to China, and the quality of what was build never dropped, but the designs started to get cheaper and sucking due to that alone.

Thanks for that input. I emailed some time back and asked if they'd considered making holders for DA or small ER collets. They hadn't but thought it interesting. I'll be wary of buying if they do, maybe buy one first to check it out. If I ever get my shop built back up once down under, that's something I'd thought about making. (DA/ER holders)

Depends what you are doing, but less is better. I have several such Sherline holders, including some 1/8" that at the time, was a custom order. All have detectable slop, though I've never bothered to measure. It's not much, and I generally stick to 2 flute mills, and set the corners 90 degrees to the set screw to minimize runout.

Why are you associating a name brand like Jacobs with a no-name junk chuck? I've got a couple keyless Albrecht -type- chucks I'm sure were made in China, brand name "Golden Goose". They are not Albrecht in quality, but more than good enough. (Also have a nice set of Albrecht chucks from zero to 1/2" capacity...)

Jon

well, I've seen the old Jacobs chucks and I have a new one. The new one works, but feels like something from a $10 power tool. I can't imagine mine is a fluke.

Counterfeit perhaps?

Ok, I missed that somewhere. Yeah, most anything new isn't going to have the fit and finish of something made 20 years ago...

Jon

it's from sherline, not ebay, and works as it should, but it's no gem by any means.

Machine size does not matter.

The smaller the end mill diameter, the more important it becomes to minimize runout.

Works well with reamers but not so sure end mills stay put.

What amount of run out would have you worried for what you do?

I'd assume that wobble with an endmill would make wavy patters in addition to wearing one or more flutes and just letting the others rub.

Also, is there any reason NOT to use a lathe chuck in a mill as a chuck for larger drill bits?

I had to drill 5/8" holes in Al plate and got a 5/8 bit with a 1/2 shank, but had no 1/2 drill chuck so I moved the lathe chuck into the mill and used that.

Of course, it spun out a few times leaving drag marks on the drill bit, but is doing this more dangerous in that you may launch a drill bit by into your chest or something like that?

It doesn't seem like you're going to kill yourself with sherline, but I'd rather not take up bad habits.

What is meant by tap the end mill?

As I said earlier, depends on the diameter of the end mill....

With a 1.00 inch endmil 4 flute, in wraught aluminum, you're going to have a chip load per tooth of about .025...so for example 5 thou TIR would be no problem whatsoever, one tooth gets loaded by an additional

But with a .093 end mill, you'll be running with a chip load per tooth of about .0003....so what happens here is with .0003 runout, a single tooth ends up taking the entire load.....in other words, once per revolution, you are subjecting the cutting tool to 4 times the stress and so depending on the work and cutter material, you'll either experience breakage or rapid dulling, perhaps both.

I guess as long as the bearings can handle it then it shouldn't be a problem with the sherline/ taig stuff--I'm assuming that their mill and lathe spindles are of identical construiction.

You might want to use drills that have 3 flats ground onto the shanks to prevent slippage if you do this again...

I think you're worrying too much--a 4in diameter chuck at 2400 rpm calculates out to a surface speed of about 2500 feet per minute which only equals about 28 miles per hour so while it might smart a bit it's probably not going to do much serious bodily damage if a hss drill bit simply gets slung sideways out of the chuck.

On the other hand, from what I understand, carbide fragments can and sometimes do attain fairly high velocities when the compressive limit is exceeded--I don't have any figures available and no time to look into it but if I recall correctly, they can approach the muzzle speed of small arms fire, small particles imbedding themselves fairly deeply into the skin under "optimum" conditions...

BTW, my youngest son has a Taig, he's converted it to full cnc but he's kind of regretting having gone this route...pretty sure he's going to buy a cast iron table from Grizzly as a "replacement part" and use it as the main base for a double column gantry mill with R8 spindle...

Similar to this, only table top sized:

You get a soft piece of brass or lead and you tap on the end mill where the dial indicator shows the runout to be high. This maybe in several places. You keep doing this till you have the least runout possible. It's a very common procedure in machining jobs shops where you have tooling that's been used and abused. Would you like me to see if I can find a video for you that will walk you though the procedure?

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For a Sherline, probably a short piece of 3/16 diameter brass rod and a jewelers hammer would be about right.

jewelers hammer would be about right.

ok I know what you mean. I've been tapping on stuff to get in to seat right in the lathe chuck. Soft stuff seems to get pinched between two of the three jaws or just lines up in off angles if you just start to clamp down on it.

They make those, as well as higher quality chucks. A look at their website will show you both.