Author Topic: quick change for hobbiest?  (Read 240 times)

Offline kjlpdx

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quick change for hobbiest?
« on: October 28, 2020, 00:01:09 am »
i am not doing production work but do tire of changing bits, re-zeroing, and all.  i have R8 collets on a water cooled 5kw(?) motor.  what options are available for simple manual bit changing?  are there adapters, or did i buy the wrong style of motor?  i work almost exclusively with plywood.  do i lose available Z axis travel with adapters?  my CRP4848 has 6" currently.

Offline lloydsp

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Re: quick change for hobbiest?
« Reply #1 on: October 28, 2020, 00:36:46 am »
You do lose some Z travel when using most adapters.  You might consider a "z-setter", which determines where Z=0 is for any given bit in any given holder.  Most CNC softs include the ability to auto-Zero a cutter.  About the only thing they don't work well for is Forstner drills with pilots.  Even then, you can make a tiny hole in the Z-setter's 'shoe' to accommodate the spur, so long as its diameter is smaller than the smallest other cutter you use.

My Forstners also have 'flush-cutters', so they're not managed by a tiny hole.  It takes a hole almost the diameter of the drill.  So I made two 'adapter' shoes for my Z-setter, so most cutters can use the flat adapter, and Forstners can use the one with a cavity in the middle.  I use almost entirely one diameter of Forstner drill for the contract work I do.  If you have multiple sizes to deal with, it might involve having more than one 'holed' adapter for the Z-setter;  but that's a minor thing.

Lloyd
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Offline Bob La Londe

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Re: quick change for hobbiest?
« Reply #2 on: October 28, 2020, 03:51:04 am »
R8 with a draw bar?  Look at using a 3/4 collet with TTS(tm) style tool holders.  The collet nose is ground flat and tool holder collar registers consistently against the spindle face. 
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Offline Bob La Londe

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Re: quick change for hobbiest?
« Reply #3 on: October 28, 2020, 03:53:51 am »
P.S. If you have a lathe you can make your own, but TTS from Tormach are very reasonably priced.  ( and hardened )
« Last Edit: October 28, 2020, 16:22:22 pm by Bob La Londe »
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Offline Bob La Londe

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Re: quick change for hobbiest?
« Reply #4 on: October 28, 2020, 16:36:34 pm »
You piqued my curiosity.  I could not find a liquid cooled R8 spindle.  Typically anything you find on a moving gantry machine (with rare exceptions) is available for general sale. 

I wonder.  Were you thinking of some kind of swap from a typical ER Collet water cooled spindle to an R8 spindle?  That might not be practical.  However for about 3-5 times the price of a decent quality water cooled ER Spindle you can get a water cooled ISO20 spindle.  I am running Powace/Rattm 1.8Kw ISO20 spindles on 2 machines and so far have been quite satisfied with their performance.  Quick tool changes using the lengths stored in the tool table. 

They are longer and a little heavier than the 1.5Kw spindles they replaced.  The swap out was pretty easy after figuring out the air requirements. 

As to clearance, of course the tool holders do stickout a little, but the solution may simply be to mount the spindle a little higher than it was mounted before.  They do caution NOT to clamp around the area of the spindle where the bearings are located. 

You can get ISO20 tool holders in both ER16 and ER20 so you could use your existing collets to start with. 
Getting started on CNC?  In or passing through my area?
If I have the time I'll be glad to show you a little in my shop. 

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Offline kjlpdx

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Re: quick change for hobbiest?
« Reply #5 on: October 28, 2020, 17:52:51 pm »
I am quite mistaken, I have the standard ER20 collets [at least I got the R part right  :) ]  i forget what power spindle i have, it is plenty powerful enough for what i do now.  like i said, i'm a hobbyist and seem to always be making prototypes.

Offline kjlpdx

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Re: quick change for hobbiest?
« Reply #6 on: October 28, 2020, 19:45:59 pm »
it appears what i'd like doesn't exist.  i realize that the spindle shaft i have just isn't big enough for one thing to accommodate say an ISO20 collet.  the only solution i see is to buy a set of collet extensions, using one for each size bit i want to use and then mount those in the existing collet, bottoming their shaft out and recording the Z height for each tool for easy repeatability.  i do have auto zero function with mach3 which i use a lot.  mostly the hassle is having to use 2 wrenches to remove the collet nut, removing the collet and installing the new size collet and then re-zeroing the bit.  i suppose simply buying more collet nuts could be half of the solution. i've seen these plastic collars that act as a stop to set depth repeatedly.  i wish the spindle had a button to lock the shaft like my routers have, so i dont need 2 wrenches, but i realize that risks bumping a stepper motor and losing location when tightening the nut since i'd be torquing against the spindle.

Offline lloydsp

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Re: quick change for hobbiest?
« Reply #7 on: October 28, 2020, 20:56:38 pm »
KJL,
Most such chucks require two wrenches.  Even my high end router spindles require them, and I paid a 'pretty penny' for each of them.

The 'secret' is to get a collet AND taper for each bit you use frequently, and _keep_ them in their holders.  Then the auto-Z function serves you well.

Lloyd
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Offline Bob La Londe

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Re: quick change for hobbiest?
« Reply #8 on: October 28, 2020, 22:16:23 pm »
Anything you "add" to your existing spindle is going to result in stackup of runout (error) and extend your spindle. 

With your setup your best option is probably an expensive spindle swap to something like this:  https://www.ebay.com/itm/1-8KW-220V-ISO20-ATC-Water-Cooled-Spindle-Motor-Automatic-Tool-Changer-24000rpm/113180010578?hash=item1a5a0de852:g:Pr0AAOSwEOpdN~HP

That spindle will use ER16 or ER20 tool holders like this: https://www.ebay.com/itm/NEW-ISO-20-ER20-35mm-Tool-Holder-Balanced-to-30-000-RPM-Cheapest-USA-Supplier/123579034483?hash=item1cc5e26b73:g:SHMAAOSwzhFcL8e0

You will need a 4way 5 port valve, decent supply of dry air, 3 regulators, a bunch of air line, and a bunch of fittings.  I am using a solenoid operated spool valve on one machine, and a hand operated mechanical valve on the other.  Either works just fine. 

I also ran a simple solenoid operated valve to cut air to the machine (air seal on the spindles blows continuously) when the machine is powered down, so it won't waste air. 


*****

If you do use the tool tables you need to send a longer string to the machine for a tool change.  This will likely require a minor mod to your post processor.  You may also want to use a custom tool change macro.  I do not keep tool number persistent.  It defaults to zero every time I turn on the machine, and I always set height to the same tool each time I start the machine.  This prevents some weird problems I have had with Mach 3 when using the tool tables for quick tool changes.  Not an issue with Pathpilot where tools section is persistent. 

Your g-code for a tool change should look something like this: 
T25 M6 G43 H25

T25 means change to tool #25.  M6 means execute a tool change.  G43 means set a Z tool height offset from the tool table.  H25 means use the height setting for tool 25. 

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If you just stick a straight shank ER tool holder in the ER spindle nose of your existing spindle you may still have some variations in height.  If everything is clean you might be able to minimize variation by tightening to the same setting every time with a torque wrench.  You might not.  A tool height setter might be a better option than using the tool tables if using a hack like you mention.  I like these tool height setters.    Its not as fast as an automated electronic one, but I have been using them for years.  I still use them every day at the beginning of a job to set the Z height for my first tool.  https://www.ebay.com/itm/Magnetic-Z-Axis-Dial-Zero-Pre-Setter-Tool-2-Height-0004-Gage-Offset-CNC-P/301203002700?hash=item462119154c:g:OUYAAOSwSxpdTG35
« Last Edit: October 28, 2020, 22:22:19 pm by Bob La Londe »
Getting started on CNC?  In or passing through my area?
If I have the time I'll be glad to show you a little in my shop. 

Some Stuff I Make with CamBam
http://www.CNCMOLDS.com

Offline EddyCurrent

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Re: quick change for hobbiest?
« Reply #9 on: November 18, 2020, 19:49:48 pm »
I just came across these quick change chucks if any use; https://www.musclechuck.com/shop/

This video is particularly interesting; https://www.musclechuck.com/musclechuck-assembly-instructions/#21 (Quick Change Router Chuck- Setting Rings)
« Last Edit: November 18, 2020, 20:27:52 pm by EddyCurrent »
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