Mill arrived

[PeterT]

Yes, most R8 spindles have something like a dog point set screw that protrudes into the bore. The the arbor has slot that engages over the set screw. Supposedly it is there to prevent the tool from rotating as you are threading the drawbar. It is not really a key like a shaft key. R8 clamping force/ seating comes from the mating tapered surfaces. Some people remove the screw altogether, I suspect most leave it in. They can unscrew & drift in over time & that can be problem so be aware of that.

I don't think you have this issue as your runout problem, but something to be aware of on this topic. Some of the offshore manufacturers are sloppy when it comes to their slot dimensions. Sometimes too skinny or shallow or both. The set screw can then drag, even hang up & get stuck. That is a real headache & why some people despise them. So whenever you get a new R8 tool, don't assume its good. Gently push it up all the way finger pressure. If no scraping friction & taper seat engages fine, you are good to go. Test#2 check the drawbar threads by hand tightening too. It wouldnt be the first time they did a bad threading job or sent a mislabelled different thread.

 

[MooseMeat]

Yes, most R8 spindles have something like a dog point set screw that protrudes into the bore. The the arbor has slot that engages over the set screw. Supposedly it is there to prevent the tool from rotating as you are threading the drawbar. It is not really a key like a shaft key. R8 clamping force/ seating comes from the mating tapered surfaces. Some people remove the screw altogether, I suspect most leave it in. They can unscrew & drift in over time & that can be problem so be aware of that.

I don't think you have this issue as your runout problem, but something to be aware of on this topic. Some of the offshore manufacturers are sloppy when it comes to their slot dimensions. Sometimes too skinny or shallow or both. The set screw can then drag, even hang up & get stuck. That is a real headache & why some people despise them. So whenever you get a new R8 tool, don't assume its good. Gently push it up all the way finger pressure. If no scraping friction & taper seat engages fine, you are good to go. Test#2 check the drawbar threads by hand tightening too. It wouldnt be the first time they did a bad threading job or sent a mislabelled different thread.

I think you really nailed it, this collet was very tight to draw up and release, then the runout, the link I posted is the actual tool from the amazon, I just went through the process of returning it and ordered a better quality (we'll see) one.

I love all the expertise here and wisdom, why in the hell isn't there an elder hobby skool that a a person can attend, I would sign up in a heart beat along with welding. There is money to be made in us approaching old farts don't they know, after all we invented the wheel.........

 

[Susquatch]

@MooseMeat - Since the mill is new, I suspect there was nothing wrong with the arbor. More likely the set screw @PeterT described is adjusted too deeply. Try another R8 tool.

Also try to see how deep the set screw dog point is by blackening or bluing the groove to check for interference. Sometimes you can see the scratches in the groove without bluing.

Lastly, some mills have an oval or longer dog point. If you have one of these, it might not be aligned vertically.

 

[MooseMeat]

@MooseMeat - Since the mill is new, I suspect there was nothing wrong with the arbor. More likely the set screw @PeterT described is adjusted too deeply. Try another R8 tool.

Also try to see how deep the set screw dog point is by blackening or bluing the groove to check for interference. Sometimes you can see the scratches in the groove without bluing.

Lastly, some mills have an oval or longer dog point. If you have one of these, it might not be aligned vertically.

I looked at the parts diagram to find the set screw, (craftex 603 mill) I will try another arbor as my tools start to show up, I'm not sure where to start taking things apart if the set screw is too deep.

 

[Susquatch]

I looked at the parts diagram to find the set screw, (craftex 603 mill) I will try another arbor as my tools start to show up, I'm not sure where to start taking things apart if the set screw is too deep.

On most of the mills I have looked at (not a huge number) there is a hole in the spindle quill that can be used to access the key in the spindle shaft inside it.

If it looks like this, the nose cap must be removed to a access the set screw.



Or this:



In both cases, there are likely two or three set screws stacked on top of each other.

The set screws look like one these



The bottom one is stronger but can get misaligned more easily.

Anyway, start with a new collet, insert it and then check for marks. Here are two collets. The left one shows the marks I talked about earlier which indicates a set screw set too long. The other is ok. Bluing will show this even better. Both of these came with my mill. Obviously, the previous owner was not aware of the problem.

 

[PeterT]

Not sure if I am interpreting the example parts correct but it would be a poster child example of what I was talking about - sketchy slot dimensions. Looks like the left one had set screw skid marks at end of red line. Take the same line length & transpose to right collet. No problem there, the slot extends as it should. You could have a scenario where its just at the perfect wrong spot where it is adversely affecting the taper seat. Sometimes the slots are the correct length but incorrect saw width, same problem.

The screw @Susquatch shows with the cylindrical end is called a dog point screw. That's the part that engages within the slot. Some cheapskate or unwitting companies put a set screw in there which is of course wider on the full threads, which has the potential to bind the slot. The other important thing is there are usually 2 screws - the dog point pointing in the spindle and a set screw behind it to hold the dog point in position. If the dog is in too deep, you loosen the set screw off, adjust the dog, then set it in place. A bit of blue Loctite is not a bad idea.

 

[MooseMeat]

On most of the mills I have looked at (not a huge number) there is a hole in the spindle quill that can be used to access the key in the spindle shaft inside it.

If it looks like this, the nose cap must be removed to a access the set screw.

View attachment 69453

Or this:

View attachment 69454

In both cases, there are likely two or three set screws stacked on top of each other.

The set screws look like one these

View attachment 69455View attachment 69456

The bottom one is stronger but can get misaligned more easily.

Anyway, start with a new collet, insert it and then check for marks. Here are two collets. The left one shows the marks I talked about earlier which indicates a set screw set too long. The other is ok. Bluing will show this even better. Both of these came with my mill. Obviously, the previous owner was not aware of the problem.

View attachment 69457

Two collets just showed up at the door, a drill and a collet holder, both fit perfectly in and out, runout was almost 0 on the drill one and the collet holder was a couple of thou, looking now like I got bad parts. I ordered a nicer boring set with replaceable carbides at almost double the price, probably should have done that in the first place as I have hundreds of cutters from my lathe purchase.

On the craftex mill there is no access to the screw, there are however what looks like two holes for a wrench to unthread the spindle collar like the ones used on grinders.

 

[PeterT]

It might be like Bridgeport/clones. The end cap comes off & it exposes the the set screws. Note end cap thread direction! I would loan you my pin wrench but its a family heirloom LOL
But if your new tooling is fitting than maybe you just had a trouble maker slot

 

[Susquatch]

But if your new tooling is fitting than maybe you just had a trouble maker slot

Sooner or later he is gunna need to get in there. I'd figure it out now.

runout was almost 0 on the drill one and the collet holder was a couple of thou, looking now like I got bad parts.

Doesn't make complete sense. Usually collet holders are better than end mill holders (assuming that's what you meant). Are you measuring at the internal collet taper (that's what matters) or the holder body?

 

[MooseMeat]

Sooner or later he is gunna need to get in there. I'd figure it out now.



Doesn't make complete sense. Usually collet holders are better than end mill holders (assuming that's what you meant). Are you measuring at the internal collet taper (that's what matters) or the holder body?

I was measuring the smooth area just above the nut on the collet holder body, I wanted to see how much attention to accuracy these chinesium tools carried, fit and finish is very nice on the last few tools that showed up, unlike the boring bar and holder. I guess I'm trying to get the best tool for my budget and not garbage in garbage out, If the tools run true then the only excuse is me..

 

[MooseMeat]

It might be like Bridgeport/clones. The end cap comes off & it exposes the the set screws. Note end cap thread direction! I would loan you my pin wrench but its a family heirloom LOL
But if your new tooling is fitting than maybe you just had a trouble maker slot

View attachment 69467View attachment 69468

ahh, got it, thank you

collet holder body

It might be like Bridgeport/clones. The end cap comes off & it exposes the the set screws. Note end cap thread direction! I would loan you my pin wrench but its a family heirloom LOL
But if your new tooling is fitting than maybe you just had a trouble maker slot

View attachment 69467View attachment 69468

If I make one of these tools will I be sued for patent infringement? 😉

 

[Susquatch]

I was measuring the smooth area just above the nut on the collet holder body,

Measure it on the inside taper.

Where you measured it would definitely indicate quality, but not the runout of the collet holder. It is likely that the body was made first and the collet taper and arbour second. Only the runout between the two tapers with respect to each other really matters.

Use a plunge indicator mounted at a right angle to the taper surface. Dial test indicators are good too but the don't really measure absolute runout. If you do use a dial test indicator, make sure the axis of the needle is as close to parallel to the surface of the taper as possible.

 

[Susquatch]

If I make one of these tools will I be sued for patent infringement? 😉

Not too likely. Peter's patent on that expired before he was born and now everyone is busy re-inventing the wheel.

If he gives you a hassle, give me a shout. I reverse engineered his from first principles and came up with a totally different and much better design. I'll happily give you a free license to copy mine.