Denford Orac problem

[marcel beaudry]

hello
my tools are parallel it will work better this way if your tools are sloped you will have a hard time putting them center of your parts and your bushing for drilling will be off centered .
marcel

[cjmerlin]

Hi Marcel, Thanks for that I guessed as much. Trouble is, When I bought the machine I was given the original single tool holder so I am guessing that the guy purchased the toolchanger and fitted it himself.

I shall try and get it sorted by a bit of trial and error until I find the right thickness for the spacer plate.

Kind Regards
John.

[marcel beaudry]

john
my plate mesures .198 inch if you want a real fast method take a lot of printing paper mesure put it under your toolholder and see how it goes it is the fastest way .

[cjmerlin]

Hi Marcel, Thanks for that. I'll check it out tomorrow.



Kind Regards
John.

[davidimurray]

Hi John

Only just found this thread - use an Orac with a toolchanger at work quite often. You shouldn't get any chatter problems - we have used it for 1mm deep cuts in EN24T steel and they came out beautifully. You mention shimming the tools - with a tipped tool the tip top should be level with the top of the tool body. With the packing plate in you set one tool to the correct centre using the adjusting set screw and then the rest should be fine - this should be pretty close to horizontal.

If I read it correctly you are missing the plate and having the toolholder at about 10 degrees of angle to get it on centre? Am I right? Might know someone with a toolchanger in pieces so I can try and get a drawing of the plate if you like.

Gotta go - limit switch problems on my mill 

Cheers

Dave

[cjmerlin]

Hi David, Thanks for the info, I'm just waiting for the new chuck to

arrive and time to fit it. I made a plate to bring the toolchanger

up. I now have the drill positions correct and my insert tool needed

0.4mm packing. I guess this is right, I would have liked a bit more

space above the tool as sometimes I use tools made from HSS stock and

after a few regrinds especially with parting tools they'll end up

below center.

What's the largest radius insert you have used on the Orac.


Kind Regards
John

[davidimurray]

Hi John

I presume you are going to have make a new backplate for the chuck? You may want to put the old toolpost on for that as I had to make a special toolholder to step the tool out far enough to machine the plate. Ours had a damaged power chuck on it when we got it so there was no backplate available.

On the toolchanger front we don't use any packing at all - when we do use HSS you just have to be very careful grinding it! If you actualy want to know the largest tip radius it is 6mm - a round nose profile tool! That tool did a hell of a lot of working making long slender specimens and the only time we had chatter was when we ran the spindle too fast. Normally I think we run .4 or .6 tips - depends on whats lying around at the time!

A friend of mine has a toolchanger for his Orac which when it arrived refused to work - a strip down revealed that the grease inside had solidified preventing the motor from turning anything!

I presume you have physically tried moving the front (tool) plate back and forth and checked the tightness of the 3 screws that hold the plate on ? There is not much to really go wrong inside them!

Cheers

Dave

[cjmerlin]

Hi David, I'm planning to use the old back plate as it has plenty of thickness, just machine off the old location step and turn a new one. I have made a tool that fits in the tool changer and has enough reach to do the job.

I've over hauled the tool changer completely. Well, tightned everything up and adjusted the bearings. I'd like to sort a better motor as the toolchange is dog slow. I thought it might be better using a stepper motor like the Boxford toolchanger.

You dont happen to still have the power chuck do you?

[davidimurray]

Hi John

I've been building the controls for a friends Orac toolchanger. We're also thinking of swapping the motor for a stepper - probably a 17 frame and use a 555 timer to generate step pulses and simply toggle the direction line. I don't think there are any major issues with leaving the stepper pulsing away while its stalled but I need to do some further research into this. The big question is what torque rating to go for.

The power chuck is still around somewhere - unfortunately its in quite a few pieces with a smashed front plate as somebody drove the tool into it before it was put into store! It's not great as the air supply comes up the spindle so you can only put about 2 inches in the chuck - i.e the depth of the chuck.

Cheers

Dave

[cjmerlin]

Hi David, Leaving the stepper pulsing away while stalled will drive you mad after a while. The one on my Boxford uses a stepper and when it reverses back onto the stop it still pulses for a second or so creating a very loud buzz that vibrates through the whole machine.
The ideal situation would be to use a small microcontroller to do the job and connect to the serial port leaving more printer port pins available.

Other than that you could use a couple of 555 timers, one to provide the pulses and use the position sensing gear already in the toolchanger and then another activated when you toggle the direction line to give say a 3 second reverse onto the stop. A powermax ll stepper with 2 amps per phase on a L297-298 setup driving the worm gear direct would be ideal.


Same about the power chuck, I've seen similar on ebay and wondered why anyone would want to use a power chuck if you cant run a bar through it.

Kind Regards
John