Automatic Tool Changer - Almost Finished Photos

[appicnc]

Hello Group

Here are some more photos of the ATC I am working on, this ( if it works ) should be very close to the finished item.

Some " issues " have cropped up along the way which have caused some minor!! changes, originally I was going to use a pulley that was about 29mm in dia'. as the spindel is 20mm in dia' not much of it was left after boring, so I went to a 30 tooth ( about 46mm ) but the problem was then seen as turning that size pulley on a 6.36mm shaft ( out of the router trimmer ) I then bought the die grinder which has an optional extra of a 8mm dia' collet, which is ordered and will be her Tues' - Wed' ( the bolt in the pulley is just for show )

As it turned out that was a mixed blessing as I had made the router holder/s and then needed to turn up a bush ot suit the smaller die grinder, I bored the centre hole off centre ( so I guess it really isn't a centre hole ) which allows some adjustment to the belt tension.

Note also gap between the air cylinder and the spring - now no need for another bearing to de-spin the spindel before the air cylinder.

The arbors are held firmly in place so I am confident it will work when powered up.

Any questions, comments or suggestions???

Ed

[Switcher]

appicnc, Looks Good!


Why did you start a new thread for this project?

How is the tool fixed in the arbor ( http://www.cnczone.com/forums/attach...9&d=1163225172 )? Did you have a collet? That would be a nice feature (Different size collets, with the same OD, different ID), then you could swap out the collet, and have different size shanks on the tools you work with.

Do you already have cnc router to add this ATC to?

How about a video, after you get it finished?





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[appicnc]

Hello Switcher,

I posted a new thread because I thought it was past the concept stage, should I have just left the original thread??? I'm not sure of the etiquette.

The bit is held in place with a 4mm grub screw, the arbors were cnc machined ( on a HASS machine - I don't know the model number but it is a pretty schmick machine ) I guess you could use larger dia. bits but all I needed when I designed it was to use 1/4" bits, the thought of a 3hp router worries me a bit to thats alot of power.

I have posted a photo of the machine I am using, I am thinking of building another one but will finish the ATC first, the new one would use belts not acme screws, I have made several changes since this photo, the belt connecting the X axis screws now has a tensioner fitted and both X axis lead screws now have a 2 - 1 reduction fitted. At the top of the photo is a unfinished model I cut out using a CNC laser I built in 1996, AH-HA! electronics, designed by a " industrial designer " here in Bathurst, it was 1200mm square and crabbed ( only one side driver ) hence my driving both X axis sides.

One problem with the larger bits would be the arbor is about 28mm in Dia' and with the current design with a 12mm bit you could only get a hole about 20mm deep, either the shank would need to be shortened or a longer arbor made, the power / speed of a bigger router may be a problem in that size tool holder, to make the arbor bigger would mean a complete re-design, still yours was a good point.

Ed

[Switcher]

I posted a new thread because I thought it was past the concept stage, should I have just left the original thread??? I'm not sure of the etiquette.

It might be a good idea to go back to your first post (on this page) and add a link to the first part of your build.

It won't take long for a thread to get buried on this site (lots of post here on the zone). At least a link will let future readers, know how you started the project.



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[Guldberg]

How does it run? Im seeing a potential problem with the spring part, at high speed my guess is that it will start to wobble. But i like the idea of having the piston decoupled from the spindle

[appicnc]

Hello Guldberg

Like you I'm not sure about the spring, it is under some compression when running and is held in place at both ends by a step in the nut and washer, if it does wobble then the design can be changed to something that a photo will describe better than I could.

Or the other option would be to use a set of belville washers, these would appear to be a better choice than a spring anyway.

I guess we will know this week if it is a goer or needs some tweaking.

Ed

[Oldmanandhistoy]

Hi,

I too would like to see a vid of the tool changer in operation. Also the link would be helpful.
Do you have any CAD drawings?

John

[GaryCorlew]

TH haas vf 4 that I run uses a spring and it is capable of running at 10,000 rpm

[appicnc]

Hello group

Quick report, I had the spindle turning yesterday but murphy came along, I had the speed of the die grinder up full = 20k rpm, the 8mm high tensile bolt holding the spring bent, the spindle bolts ( 4 x 8mm HT cap scews ) came loose and I needed new underwear.

I replaced the bolt and re-tightened the other bolts and tried again, up to 7k little if any vibration but above that vibration increased rapidly to a point that I think the whole Y axis would vibrate, I have ordered some Belleville washers and hope to fit them today.

That should take care of the out of balance that is in the spring ( which is fine for no speed or low speed but as it turns out isn't fine for hi-speed ) and at the same time is easy to fit and provides plenty of " pull ".

I'll let you know how it goes.

Someone asked about CAD plans, I do have them but am not sure what to do with them, I was thinking of selling the three main parts ( spindle, gripper and arbor/s ) and giving the plans away with the parts ( to work well the parts need to be well made, my thinking was / is that cnc'd parts should fit, work well and be interchangeable. The downside with that approach is the parts cost me more than most hobbists may wish to pay. The other problem with selling anything, there is still some work to do to get it all working and I'm then " responsible " for the whole article.

Any suggestions????

Ed

[ViperTX]

Just a hint....find a way to decouple the spring from the rotating unit....I would look at something like a bearing....

[skippy]

Unless you can find a way to do as ViperTX suggests, I would attack this in another way. To me the problem is that you have an almost unsupported spring out there in the breeze causing lots of potential problem due to movement/vibration/etc. One possibility would be to use an internal or external supporting sleeve for the spring however I still don't like that idea much.
Although it would need a minor redesign to do so, I'm convinced the spring could reside inside the unit so that its furtherest most extremity (on the left using picture 3) would be in line with the pulley face (on left). Yes the pulley would have to be bored out, etc. to do so but in doing so you reduce the overall length therefore the leverage factor and the spring is supported inside body. It appears to be an automotive valve spring that you are using so possibly you could use a small diameter one from a smaller motor or from a 4 valve engine in order to have it fit inside bearing etc. Just my $0.02

[Rance]

Ed, Please either remove the pic in post #3 or retake the shot WITHOUT the strain on the gray and white wires. It hurts my eyes when I look at that picture. Seriously, nice work. I'd like to see you take this to completion.