[nine 16]

Hoss2006,

You are an inovative machinist to be sure!

Having just read this thread I do not recall seeing Z repeatability specifically addressed. If I'm picturing this right, an upward-biased spring-loaded drawbar will be in threaded connection to an R8 collet. When said drawbar is forced downward the R8 will disengage from the spindles non-locking taper and release its grip on the tool holder.

The tool holder itself will rely on it's flange contacting the botton of the R8 for Z control. The R8, if I recall, has a longitudinal indexing slot, so it cannot rotate.

Is there a need to positively restrain the drawbar from rotating? Is it assumed the springs will accomplish this? If the the drawbar does rotate a bit over time, might it not effect spring tension and might not the Z drift also? I understand that uniformity of tool holder shank diameter is important, but is that alone sufficient to deliver repeatable non-drifting Z?

Thanks, later
-Mark

[hoss2006]

Hey Nine,
With 600 lbs or more of spring pressure exerted on the drawbar constantly,
I don't think loosening will be much of an issue, but time will tell.
When it's at tool change, the spindle will be stopped (i hope) and the pin should keep the collet from being able to rotate.
No matter how much pressure is exerted, the collet isn't going to any higher than the point it clamps ahold of the tool.
The spring washers will wear out as time goes and need tightened or replaced.
I'll be leaving enough room to access the drawbar manually
since I still want to be able to use my other R8 tooling for other jobs.
I have another cool project in the works too, but can't test it till the mill's back up and running.
stay tuned.
Hoss
http://www.hossmachine.com
Note: the server was down for a couple days, they cost me money from the
missed clicks on the google ads.
One more time and i'll be going to GoDaddy.

[nine 16]

Hoss2006,

Yep. Restraining the drawbar from rotating should not be necessary. Even if it does rotate over time somehow contributing to Z drift, occasional Z rezeroing will make it moot. As long as the tool holder shanks are 'equal' in diameter the R8 will be prevented from collapsing more, or less, and disturbing Z too much. It is an X2 after all; mods such as your can easily be of equal or greater tolerance than many of the stock head and spindle components anyway.

Keep it up.
-Mark

[Bob Adams]

Your webpage is still down can't access it.

[hoss2006]

bob,
should be ok now, just checked again.
they posted a backup from last month, i had to re update it for today.
try hitting reload if you use firefox.
hoss
http://www.hossmachine.com

[hoss2006]

Hey mark,
you're right, I'll bet my quality assurance department is a little more picky
than the ones in china.

[Bob Adams]

Hey Hoss, no go on your webpage. What happened to your Yahoo group?

[pastera]

Hoss

For Z repeatability take a look at the Tormach tool holders - I made a few knock-offs for my X1 and the Z is repeatable of a range of drawbar tensions.

Aaron

[hoss2006]

Tormachs would be nice but $$
My knockoffs are all within .001 inch of each other and nearly free.
besides, like the CNC guy at work says, when he sets up a job, he sets each tool that will be used to the part being machined. Different sized holders will require different offsets.
if I need to have several tools exactly the same distance to the end of the cutting edge, i'll use a height gage and ground tool set like LMS sells with their Tormach kit.
ooh, need to get making that ground tool set too.

[snowshovelbmx]

Those toolholders look really nice! I will have to make a couple for myself one day. You might consider putting an undercut on the tool holder though, so that the holder does not sit against the collet but rather it is supported by the spindle itself. This is how the tormach system works and I think it contributes greatly to the repeatability and rigidness of the system.

chris.

[hoss2006]

I see what you mean Chris.
i.e. this tormach tool holder
I made mine 1.250 O.D. though, have to check to see if it will still mate with the spindle.
Wanted to make them small enough to fit (4) in a tool rack on a stock X2 table.
Back to the drawing board?

[pzzamakr1980]

Hey hoss, I've been using the tormach system for months now and have to say it is fantastic. If you would like a suggestion, get the collet and a few blanks and make your own stuff. The collet is cheap and the blanks are really cheap and you can make anything out of em. I needed a jt3 or 4 mount for the big drill chucks and I used a blank to make one and it came out great. I also used the blanks to make some endmill holders. The little lip which makes the tormach special and nice to use for toolsetting was really difficult for me to make nicely and rather than go to the trouble of trying to make it as precise as it should be, I just bought the blanks and its done for you as well as the shank to go in the collet.

[pzzamakr1980]

I've got a few more thoughts too. What makes the tormach starter sets so expensive are the er-20 collet holders. I use them because the 1/4 collets that I use, especially now the carbide ones I just bought, dont seem to like end-mill holders. I also use them because they are very small, very little Z lost, and have a excellent runout which is perfect when I use really tiny drills and soon when I use small endmills. But if you're not using collet holders than the endmill holders and the drill chuck adaptors are pretty cheap. You can get the drill chucks from 800watt for the keyless ones in all size ranges all for less than 20 bucks and then put the adaptors in for the tormach system. All the 800watt ones can be sold to you unassembled so you dont have to remove the drill shank. Also, if you really like the er-20 collet holders, 800watt has a whole set of em, and they are pretty nice, for like 60 bucks. I realize that I seem to be pimping 800watt a lot but he sells some pretty decent stuff for cheap. And being a college student who's trying to start a small business doing this stuff, cheap is sometimes all I can do.

[hoss2006]

I've dealt with 800watt before and it wasn't good.
I was one of the number of people that did not get good service for some reason.
I had to get Paypal arbitration involved to get him to finally ship my order, months later.
Too bad, he does have some good deals.
I'll look around Ebay, I'm sure others have just as good a deal,
Thanks Hoss

[hoss2006]

Chris got me thinking, I'll design this to use tormach tooling from now on.
If someone wants to use them, they can, or they can make their own.
I'll changed my prints for the tool holders to be 1.5 O.D. with the same recess for the R8 collet.
This will limit the # of tools to 3 per row for a stock X2.(6) total (Phase 1).
that should be plenty to handle a job.
I can still use my tool holders, tormach makes a conversion kit for other tools. Read the Datasheet.
This will solve a couple of problems that were looming too.
Looks like I'll still need to modify a 3/4 collet like tormach recommends.
or buy one.

[Bob Adams]

Here's Handy Free program to calculate cylinder force at 0 to 90 degrees.

[hoss2006]

Too Cool,:wave:

You are the Man Bob! :cheers:
Thanks, Hoss

[Bob Adams]

Here's my preplan for my machine please add any input.

[hoss2006]

Hey Bob,
I like the lever design, leaves plenty of access to the drawbar for manual removal.
I think though that with 600lbs or more acting on the the drawbar,
it may want to cause the mounting plate to flex back.
maybe add a second on the left side of the head and a cross brace between them. That's the way i'm going. Just my 2 cents.

I have all the electronics in one enclosure now, will keep everything neat and tidy.
Got the Spindle motor to turn on/off using M3/M5 in Mach 3 yesterday with the Cnc4PC board.
Fought with it all day Sunday thinking it was a hardware/wiring problem, turns out it was in the many Mach 3 settings.
Tried something different than what was spelled out in the basic instructions, and it worked. (more later)
Works pretty cool now. made a little program to tell it to turn the spindle on (M3) at S4200(my max RPM),
move the X 10.0, then turn the spindle off (M5)
then repeat using a (S)peed of 2500.
It spun slower the 2nd time.:wee:
Now to add a switch so that I can choose between running the Spindle manually like before or by Mach 3.
Hoss
http://www.hossmachine.com

[Bob Adams]

I Like your 2 cents. What sensor are you using for the RPM? When can we see something?