motorized casting machine problem

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andychar
Posts: 4
Joined: Thu Dec 17, 2015 2:16 am

motorized casting machine problem

Post by andychar » Thu Dec 17, 2015 3:38 pm

I have a very old Romanoff ,motorized, broken arm casting machine. I have been successfully casting sterling silver or bronze with it for several years.

Last cast of a 4X7 flask the machine began hammering loudly, and vibrating badly, as if out of balance. (The casting arm had been balanced correctly.)

I quickly shut down, and removed the casting arm,to check the motor and drive. All was smooth there.

The hammering sounded as if the broken arm would swing from the start position, hit the stop on the casting arm and recoil to the start position.

I don't understand how the broken arm could recoil. Centrifugal force should keep the flask and arm straight out. (Could the ball bearings in the broken arm have anything to do with this?)

If any one has experience with this machine, I sure thank you for any advice or suggestions, Andy

Harold_V
Posts: 16927
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: motorized casting machine problem

Post by Harold_V » Thu Dec 17, 2015 4:20 pm

I have owned one of them since the mid 80's, but it has yet to be put in service. It was purchased with my retirement in mind. For that reason, I most likely won't be able to provide much guidance, but one question does come to mind. If there is a stop that prevents the arm from going past center when the centrifuge is activated, is it possible yours has broken? The arm may be oscillating back and forth, seeking center as it spins.

Just thinking out loud.

Harold
Wise people talk because they have something to say. Fools talk because they have to say something.

andychar
Posts: 4
Joined: Thu Dec 17, 2015 2:16 am

Re: motorized casting machine problem

Post by andychar » Thu Dec 17, 2015 9:58 pm

Thanks for the thought. The sound is, as if the broken arm is oscillating back and forth between the stops, like you said.

Nothing appears to be broke. The iron casting for the broken arm is very heavy duty. I will try to take a photo this weekend. I am new to the forum, and not sure how to post an image. It shouldn't be too difficult.

I love the machine. It is real well made, and has given me a lot of good service.

If it is of any interest to see what I use it for, some of the items I make can be seen at http://www.oldworldbronze.com Andy

Harold_V
Posts: 16927
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: motorized casting machine problem

Post by Harold_V » Fri Dec 18, 2015 4:34 am

I took a casual glance at mine today, and found that the stops are rather robust. Not likely to be broken, but if there's not much friction on the joint, I can't help but wonder if, maybe, yours is bouncing. What I don't understand is why it would start doing what ever it's doing so quickly, after serving you so well for so many years. Might not hurt to dismantle the arm to see if anything is amiss.

I took a look at your site. Some very nice things being made.

I'm curios about the large torch you're using in the video. Is it a Hoke torch, or is it just a welding torch with a rosebud? I used to have a large Hoke, but it went with the business I sold (I refined precious metals). It is no longer provided by the source from which I made my purchase, and I have been unsuccessful in finding a new source. Sad thing is, I don't recall the brand of the torch.

If you discover the problem with your centrifuge, please make mention. It might prove useful to others.

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Harold
Wise people talk because they have something to say. Fools talk because they have to say something.

andychar
Posts: 4
Joined: Thu Dec 17, 2015 2:16 am

Re: motorized casting machine problem

Post by andychar » Fri Dec 18, 2015 7:07 am

hello Harold,
The torch is a welding torch with a rosebud. I had it made up by " Browns torch and regulator repair" here, in Phoenix Az. As I recall, I believe it was about $135.00. I use propane and oxygen,however we tested it in Browns shop, and it worked as well, with natural gas.

I did dismantle the arm, and it has ball bearings, in the joint. It seems as if the arm has to move very freely at the joint. I thought it possible, the grease might be burnt out of the ball bearings, and they are stiff. ( I will check that out today )

When I find the cause of the problem, I will post the solution. Thanks for the photo post info. Andy

andychar
Posts: 4
Joined: Thu Dec 17, 2015 2:16 am

Re: motorized casting machine problem

Post by andychar » Mon Jan 11, 2016 12:53 am

I found the problem, and repaired it. The ball bearings in the broken arm were frozen, and the race had worn a groove in the axle bolt. I replaced the axle bolt and ball bearings.I don't know why this caused the machine to knock so badly, but it works fine now. Andy

Harold_V
Posts: 16927
Joined: Fri Dec 20, 2002 11:02 pm
Location: Onalaska, WA USA

Re: motorized casting machine problem

Post by Harold_V » Mon Jan 11, 2016 2:48 am

Amazing! And, well done!
One never knows how a device will respond to mechanical problems.

You may have provided guidance for others who experience the same problem. Thanks for posting.

Harold
Wise people talk because they have something to say. Fools talk because they have to say something.

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