arz

Skiving Machine, Dual Speed needed?

38 posts in this topic

16 minutes ago, Trox said:

Mine has three motors, one 380V for the knife that runs on full speed. One for the suction device, also 380 V on full speed. And a little 12v DC motor inside the head for the feed wheel. I do not have three phase (380V) in my workshop, so I just connected a frequency controller. It's plugged in my 220V single Ph outlet and four leads goes from it to the 380V inlet on the machine. The controller converts single 220v in to three phase 380V. And the hertz controller on it gives the full 50 hertz all the time, motors run at full speed as they must on this set up. That's how easy it is to do this, ask Gigi for help. By the way all AC motors are initially a three phase motor. Tor

Hmm...sounds easy enough. How much does a frequency controller cost? This machine is just like yours but does not have a servo for the feed.

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Depended of how much amp and watt the motor is on, you got to buy a little bit over size. You can get them used on Ebay. I would guess it's possible to get one new (the right size) for the machine between 50 to 70 USD. However, it's easy to rewire a three Ph AC motor to single too. All you need a capacitor to mirror one of the Phases, See pic. The bigger the capacitor is, the less torque you loose. Because, the AC motor is always stronger when it runs on three ph, than on single. Here I've have used two big capacitors instead of one. But they are connected the same way as with one. It's an 1 KW AC motor for a air compressor. The frequency controller is the best option when you need the possibility to adjust the speed of the motor. I used them on everything from sewing machine clutch motors to the skiving unit. I always have some laying around. Gigi uses one on their skiving machine too.  

I always use the easiest method when I need to connect a three Ph motor to a single Ph net. On the skiving unit I would have to rewire two motors with capasitors. Therfore I just plugged it in to a frequency controller, much easier. You also have to connect a little switch, for the startup of the machine. I only used a little lamp switch ( I used a foot button lamp switch with two wires/poles). Of course you have to read the Pdf instructions/manual for the controller.  The Watt and amp rating on the motor desides how big it has to be. This is one on 0,75 KW. The single current from wall outlet comes in on the top, the white cable goes to the start switch (lamp switch). And the four other goes to the motor conections(or machine input box).

To connect the four (output) wires for the motor: Earth on earth of course, then you just going to try with the three others. There are three contacts on the motor where they should be conected. If it doesn't start, change them around and if it starts and goes the wrong direction; change them around again until it starts and goes the right direction. There is no other way to connect these, try and fail (it's not dangerous).

With this type of controller you can control every parameter on a AC motor if needed, like tourque, speed, startup time/stoping time you name it. But in this case you do not have to do anything else than set the hertz to full (full speed) This is easy to do if you know the principals, if not get some help from an electrician.

Tor

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Before I can recommend you using one of these methods I got to see the setup, motors and the connection box on the actual machine. If there are two three Ph motors on it, one clutch motor and a regular AC motor (one speed). Then both these methods will work fine. But if one of the motors are a DC servo motor or the machine has an electronic inbuilt speed control, then it's a difficult task. It still might be possible, but a much more difficult project.   

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@Trox Thanks for the detailed info! This is a basic machine, no servo or electronic control. Atom in the UK sent me the manual so I have the electrical schematics. To be honest it may be able rewire it for 220V (it maybe 220/380V). I should have looked closer at the motors when I saw the machine. I think the dealer just doesn't want to deal with it.

I have done a fair amount of electrical work in the past. Looks like the controller would be easy to do. 

Could I just take the existing power cable and wire it into the controller (instead of wiring it directly into each motor)?

Thanks! -Adam

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22 hours ago, arz said:

@Trox Thanks for the detailed info! This is a basic machine, no servo or electronic control. Atom in the UK sent me the manual so I have the electrical schematics. To be honest it may be able rewire it for 220V (it maybe 220/380V). I should have looked closer at the motors when I saw the machine. I think the dealer just doesn't want to deal with it.

I have done a fair amount of electrical work in the past. Looks like the controller would be easy to do. 

Could I just take the existing power cable and wire it into the controller (instead of wiring it directly into each motor)?

Thanks! -Adam

Of course, that is what you do. Just for illustration I wrote it like that. I've been using these controller for many years and not had any problem with them.  

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@Trox Thanks again. I'm comfortable doing this. I did some research and it seems to be a common thing to do. This 220V machine uses 750W total. So they are not large motors. Now I just need to fine a controller that is around $50-100 :) All the local ones seem expensive. Setting up a business is expensive so I'm trying to save everywhere I can!

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If the machine can't be rewired  to a different voltage, you may be able to use a buck-boost transformer in front of it.

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I found a different Ellegi (Atom) model and bought it. It was much less than the other one, I only paid $250 for it! 

This one is newer (2001), a little better condition, was already converted to 220V, and was used by a older couple closing their shoe making shop. Works great. It has a vacuum but not a continuous running knife. For the price I paid I can easily add a second small servo motor to run the feed wheel.

At the moment it is in the back of my van until I can find help to move it (it weighs 113kg!). I'll post a photo once I get it in the shop.

Thank you for all your help and advice! -Adam

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5 hours ago, arz said:

For the price I paid I can easily add a second small servo motor to run the feed wheel.

I think you may mean the knife continuously? The blade always running at full speed works best. Sounds like a very good pick up for the price anyway. Brian

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1 minute ago, RockyAussie said:

I think you may mean the knife continuously? The blade always running at full speed works best. Sounds like a very good pick up for the price anyway. Brian

I will use the clutch motor currently on the machine to run the blade continuously (at full speed). I would like to remove the belt from the main shaft to the feed wheel and add a small servo motor for the feed wheel. That will give me great control with feeding. My thought was it will be much easier to do this than add a vacuum :) Plus for what I paid I could not go wrong. -Adam

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Ah Ha now I understand. That would probably be easier and I look forward to seeing or hearing how it works out. I'd give you hand to get it out but it's a little bit too far away. best regards Brian

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Just now, RockyAussie said:

I'd give you hand to get it out but it's a little bit too far away. best regards Brian

:) Thank you anyway, very kind of you! If/when I do any modifications etc. I will start a new post.

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On 2017/4/18 at 2:15 PM, arz said:

Hello,

I need a skiving machine (bell skiver) for splitting wallets back, thinning pockets etc,. I need it so I can line a wallet, so I have to get it down to below 1mm. Here in Europe it seems common to do that. I would be using it for 2-3oz (1mm) goat, calf and veg-tan. Maximum 2mm thick. 

My question is do I need a dual speed set-up? In other words, a constant knife speed and a variable feed wheel speed. The price difference can be almost twice. 

I have heard some say that you need the blade running at high speeds, but I also need control. Any thoughts on this?

Thanks! Adam

Chinese Leather Skving Machine......hope can help you :-)

This is the link: http://robinindustry.com/product/334.html

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