Thread: CVA mill

That is a whole lot better than my only attempt at acme. I decided that there was too much play in the cross slide screw (which was what I was trying to make) for it to be possible. The tool grabbed and pulled in by the amount of play. About 2mm. End of tool. I watched a YouTube video a couple of days ago by Donald R. Cossett. He was cutting an acme thread and had a carbide insert similar to V form thread inserts, but with the acme form.

Dean

OK I will have to use the HENDEY as this guy is

http://www.youtube.com/watch?v=EK33q1JdDnU

Hi

Discovered something relevant to cutting ACME threads . Ive been using what I thought was a free cutting steel, well it isnt . My bodge was the result of using crap steel .

Because the ACME form tool has no top/side rake , you are asking the tool to do a lot .

Im now looking for some leaded steel

Mike

I managed to pick up a 12' length of 7/8" 1214 free machining stock- from this place . I will be making the leadscrew from this stock


http://www.ian-stansfield-smith.com.au/

They have a good amount of 1214 and 12L14 , in many imperial and metric sizes in round and hex .

They sell it by weight in 12 ft standard lengths .

Mike

Ive made the newACME lead screw , the 1214 steel made a huge difference , it machines nicely .I am making two lead screws, one is for Andre , as he has the same machine- itseasy to make two of them as the lathe is set up for the job .

Next step is the nut

The old and new lead screw & nut . The nut is made from delrin , I have to machine up a sleeve for the delrin nut - it is rather long and robust for a leadscrew nut . Mike

Thanks Mike much appreciated

I am going to give my mill a lick of paint and try to remove the stuck auto lock Chuck over the weekend.

Hi

I removed the motor frame assembly today , had to use a engine crane .

Its a 3/4 hp 6 pole motor running 940 rpm . I checked the field windings insulation with a megger and it checks out OK .

Not sure if it is delta or star connected yet ? I'm getting half an ohm between each of the 3 wires

Mike

Mike were all six wires of the motor connected to the switchgear ?

Originally Posted by welder

Mike were all six wires of the motor connected to the switchgear ?

Andre

I can only see 3 wires , not 6 . Mike

Okay I have six wires on my motor.

I stand corrected my motor also has 3 wires. Do you think you can extract the star point ?

Originally Posted by welder

I stand corrected my motor also has 3 wires. Do you think you can extract the star point ?

hi Andre

One thing that worries me is the age of these motors , the old cotton insulation they used in those days has become very fragile after 60 years . If we tried to mess about and find the star point , the whole thing could become a mess and be turned into a boat anchor .

One option is to look into using a newer motor with an adapter plate . I am investigating this idea .

Mike

Mike and Andre - how about going to plan 'B' and taking the motor down to the local rewind shop? They can rewind the motor with modern insulated wire, pull out the star point (and convert to delta) and you have a VFD suitable motor in the original housing. I've been told that old insulation and VFDs don't always play nicely together because the old insulation can sometimes not withstand the square wave pulses - especially if it has been moved around and cracked in places.
Best of both worlds?

Michael