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Rockford CNC Lathe Revival

Janger

(John)
Vendor
Premium Member
Hey forum.
I keep blowing fuses trying to run the little guy at 3000 rpm. The motor says 2500 rpm on the plate. It’s a dc motor. The fuses are 8amp. There are two of them in the minarik brand motor drive. Any advice here?
 

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YYCHM

(Craig)
Premium Member
Are you just trialing here or do you actually need to run it at 3000 RPM? That's twice+ what my lathe is rated for:rolleyes:
 

Dabbler

ersatz engineer
Do you have a multimeter with a current clamp? that's the first step in diagnosing the problem
 

Tom O

Ultra Member
Can you change the sprockets to increase the rpm rather than pushing a 2500 rpm motor past its rating?
 

Tom O

Ultra Member
Same as the Haas then I have to change the feed rate from 650 to 400 for the program to work using fusion 360.
 

Janger

(John)
Vendor
Premium Member
Made a real part on the cnc lathe today. I did the roughing in the lathe but the threading I simply did manually with a die. It’s a arbor for the small drill chucks I bought. One end is .625” diameter round and the other is 3/8-24 threaded. Spun the chuck onto the arbor and applied loctite. Here are a few pictures.
 

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YYCHM

(Craig)
Premium Member
What is this thing with all the carbide tooling in it......?

d750fc84-e830-42fa-bb12-08ab12e84536-png.18935
 

Janger

(John)
Vendor
Premium Member
If you notice in picture 2 above there is also a threaded hole to take a screw down the throat of the chuck. The instructions said that should be a left hand thread and left hand bolt. I don’t have either so I just used a conventional #6-32 machine screw. I then used loctite on the threads. Will that hold?
 

Susquatch

Ultra Member
Administrator
Moderator
Premium Member
That is the rotary tool holder. Holds 8 tools. It’s motorized and spins each tool into position automatically. I still have to figure out the calibration for it. I can manually spin the tool into a close position and then use a straight edge to dial it in to centre.

Amazing that such a "quick change" tool holder has enough rigidity to actually work! I would think the cranking gears take one heck of a beating! I'd there a locking lug of some kind?
 

Susquatch

Ultra Member
Administrator
Moderator
Premium Member
I believe the mechanism is very similar to a rotary table. Worm gear?

Ya but rotary tables have a lock. Mine has two. To work with a motor drive like that, that thing can't have a lock. All the force will have to be reacted by the gear. I think it's a lot to ask of it.
 

Janger

(John)
Vendor
Premium Member
Same as the Haas then I have to change the feed rate from 650 to 400 for the program to work using fusion 360.
There is another fix for that @Tom O. In the setup for the haas post checkmark G0 for rapids. below... But perhaps that is only available if you subscribe?

1640042747611.png
 

Janger

(John)
Vendor
Premium Member
Ya but rotary tables have a lock. Mine has two. To work with a motor drive like that, that thing can't have a lock. All the force will have to be reacted by the gear. I think it's a lot to ask of it.

Hmm. As a counter example it's reasonable to turn the handle on a RT while milling. It must be a pretty fine gear as it is 40 turns of the motor to move the next tool into position.
 

Janger

(John)
Vendor
Premium Member
Videos....
Pardon the shaky camera. Tool changer.
Speeds and feeds. It is aluminium. 900 RPM. diameter about 5/8". DOC 0.010" on the diameter. Feed is 0.001" per rev.
The part is the arbor to hold a drill chuck in the 90 degree tool holder you can see in the tool changer video at the top. It needs to be threaded 3/8-24 on the small diameter section. I also need a tapped hole in the end I think #8. Post #28 shows more pictures.
 
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Alexander

Ultra Member
Administrator
This is some good work John! Also I totally agree any machine moves outside the part should be G0 @Tom O. the main reason is while proving out the program you can keep the feed rate at 100% and turn the rapid way down. This helps on the first run through a part. Depending on how your machine is set up it may actually last longer if you use rapid. Most controllers have different breaking and resolution on a rapid move than a feed move. The Mazak I run actually has sliders to adjust accuracy, breaking acceleration and resolution.
 

Janger

(John)
Vendor
Premium Member
Well folks I need some help. Kevin suggested shouting out to @RobinHood Rudy @johnnielsen @Dabbler the John's and anyone else who knows this stuff.

I was finding I can't spin the little lathe faster than 2100RPM now without blowing a breaker. While I was trying to diagnose this as an electrical problem I discovered that I don't think it is - I think it's a lubrication problem. Why do I think that? Well...I was running the lathe at a lower speed like 1800 rpm for a long time 20-30 minutes. Then suddenly I smelled something rubbery stinky, the lathe slowed way down and the current I was measuring went way up. I caught a max current on another attempt of 23A - that will trip the 15A breaker - picture 3! I hit emergency stop and noticed the headstock was quite warm AND the spindle was suddenly hard to turn. I took the belt off and the spindle was still hard to turn. Then I was looking at the oil sight glass. I thought it was ok (see below pic 5) but I grabbed some 32 oil and poured it in trying to get the level up. I then turned the spindle and amazing it spun like glass easier than it ever has. Then the next trouble started all the oil I put in started leaking out all over at both ends of the spindle. I couldn't get the sight glass fuller than just above the markers at 3 and 9 o'clock. Picture 5 below shows the sight glass. Is that too low? what is full? Is it at the top or the middle ok? That's my first question.

The second question is the leaking oil. Picture 2 shows the bearing (Timken 11162). Fitting over the bearing is the cover - aluminium - which has a close machined fit on the outer most lip to the flange outside edge. Picture 4 shows the cover. I expected to find a gasket but no. The cover and the flange have some hard black guck stuck on which might be gasket glue mostly removed? Would that be how the oil seal is made? Anyway both bearing covers leak. How would these covers be sealed? That's question 2.

Question 3 everybody is the spindle body is mated (by friction?) to the bearing inner housing and I don't know how to take it apart. I tried gently tapping on it with a dead blow and it's in there pretty good. I wanted to take it out because there is no access to the second bearing cover as seen in picture 1. How should the spindle be removed from the bearing? I've never done anything like this so I didn't feel comfortable whacking it hard. Is taking it apart a bad idea? How do I reassemble it? There is a big nut that goes on to the spindle on the threaded section just sticking out past the bearing. Picture 2. Would tightening that up pull the spindle back into the bearing properly? How tight?

Thanks!

Thoughts?
 

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