multi 12v dc take off -is this OK?

HowardGWR

multi 12v dc take off -is this OK?

Postby HowardGWR » Wed Nov 10, 2010 3:32 pm

I have a transformer from which I run the 12v dc output to my Compspeed controller on my test track.

I also have a 12v mini drill that I used to run off another old transformer / controller but this conked out recently.

I want to connect my drill so that I can use the variable input of the Compspeed. I was just going to attach the leads to the test track.

Is this likely to produce a problem for the Compspeed? I don't want to ruin anything. It has of copurse feedback settings. Does it matter which I select when I run the drill?

Any help to this total electrical innocent very much appreciated. regards, Howard

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Tim V
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Re: multi 12v dc take off -is this OK?

Postby Tim V » Wed Nov 10, 2010 5:06 pm

I would check the wattage of the mini drill, it may exceed the capacity of your controller.

New transformers are relatively cheap, for example I have a 1.5amp one that came with a parallel port scanner, the scanner is out of use but the transformer......
Tim V
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grovenor-2685
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Re: multi 12v dc take off -is this OK?

Postby grovenor-2685 » Wed Nov 10, 2010 5:22 pm

Maplins currently have a special offer on DC power supplies, a multi-voltage regulated supply adjustable in steps from 5 to 15V and capable of delivering 4 Amps. £19.99 Part no L11BQ.
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Keith
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HowardGWR

Re: multi 12v dc take off -is this OK?

Postby HowardGWR » Wed Nov 10, 2010 9:58 pm

Thanks very much Tim and Keith. I knew the advice would mean I had to spend money. :-((

Whilst I am on this, I have a similar Q on another transformer I have. It's an Emco one for the Unimat 1 lathe which I am still trying to learn to use after 25 years (!!). Frustratingly, it only delivers 6v at a constant very high speed so the lathe / drill / milling machine is useless because you can't alter the speed like you can with a normal transformer. It whizzes too fast when approaching the target with the bit or drill or milling thing.

I can't understand (never could) why all lathe people talk about working up to a speed when presenting the cutter to the work when this thing spins like a dervish and no way to change it.

So does anyone know what one could put in between the transformer and the device so one could use it like a train controller?

I can supply details of wattage, etc if that has something to do with it. I was intrigued with Tim's answer.

My mini drill is Electro Hobby. On the side it says 12 -18v Dc. 0.8 - 1. A. 11-20000 U/min.

The Emco transformer says 50-60 Hz:sek. 5V 3A 15W; T25B.

I connected the drill up to the contacts of the Emco but it just buzzed a bit. Didn't turn.

I can't understand why the transformer whizzes the lathe motor around at an impossibly intimidating speed and doesn't get the drill going at all!

I know some of you good people can solve this. These items have stared at me for 25 years on the side of my spare room, awaiting your kind help. Help!

Regards, Howard

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grovenor-2685
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Re: multi 12v dc take off -is this OK?

Postby grovenor-2685 » Wed Nov 10, 2010 10:49 pm

My mini drill is Electro Hobby. On the side it says 12 -18v Dc. 0.8 - 1. A. 11-20000 U/min.

OK Watts is the product of voltage and current so the drill is 18 Watts max. So long as your controler is rated for 1.5 Amps or more it won't do any harm to try it . A drill with such low power is not going to do much but if you are just using it for little holes it should be OK.

The Emco transformer says 50-60 Hz:sek. 5V 3A 15W; T25B. I connected the drill up to the contacts of the Emco but it just buzzed a bit. Didn't turn.

Probably because the transformer is just putting out AC rather than DC and the drill motor needs DC. in any case 5V was not going to drill anything, it might spin on 5V DC but would stall easily.

Sorry I have no idea what you might do to control speed on a Unimat 1, if its only got a 15Watt motor its going to have to spin very fast as the motor is not going to produce any low speed torque, its not going to cope with any job that needs a low speed.

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Terry Bendall
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Re: multi 12v dc take off -is this OK?

Postby Terry Bendall » Thu Nov 11, 2010 8:58 am

"I can't understand (never could) why all lathe people talk about working up to a speed when presenting the cutter to the work when this thing spins like a dervish and no way to change it."


Thomas

Most Unimat lathes have some sort of pulley system that will reduce the speed. The picture on page 7 of Scalefour News 156 shows the speed reduction system on my Cowells lathe. Unimats, as far as I know don't have the back gear system but most have a pulley system using round drive belts. If there is a small pully wheel on the motor driving a larger pulley on the main spindle the larger pully will go more slowly. Some Unimat lathes I have seen have a set of intermediate pulley that will do a compound speed reduction. This means that you have a small pulley driving a larger one on an intermediate shaft and then on the same shaft another small pulley that dives a larger one on the main spindle. This of course needs two drive belts. It is just like the two sets of reduction gears shown in the picture mentioned above.

If you can take a picture of the pulley wheel set up on your lathe and send it to me off list I will then respond direct.

Slowing down the motor itself using a speed controller will not work because you will probably reduce the power available.

Terry Bendall

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Re: multi 12v dc take off -is this OK?

Postby grovenor-2685 » Thu Nov 11, 2010 9:26 am

If you can take a picture of the pulley wheel set up on your lathe and send it to me off list I will then respond direct.

Terry, lets keep it on list so everyone learns, that's the idea of the forum.

Incidentally i think that the Unimat you are thinking of is the original Unimat SL replaced by the Unimat 3 and subsequently by the Chinese Unimat 4. I think the Unimat 1 is the plastic one with a low voltage motor.
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HowardGWR

Re: multi 12v dc take off -is this OK?

Postby HowardGWR » Thu Nov 11, 2010 1:35 pm

Thanks both. First, Terry, my name is Howard, the other is my surname.

Second, my lathe is the Unimat 1 Lathe which is the 'toy' lathe. I am going to open a new topic on my electrical problems with that and so this is the continuation, perhaps the final, of my query on connecting two outputs to the same output on my transformer for the drill.

I tried the drill (given confidence by Keith's reply) by just pushing the contacts onto the transformer 12v DC and it worked fine. It's a good little drill. However, the green light on the Compspeed lit up when the drill was being used. My question is 'is that due to the fact that it doesn't like it, or is it just registering that it is sharing the feed? More importantly, is it likely that I could be doing something I ought not?
The purpose, if you remember is that I don't have more than one 12v Dc output on my transformer and I simply want to share its output for two devices. I don't envisage trying to use the drill at the same time as running my 48xx up and down the test shunting plank. There lies disaster! I have at least learned 'one thing at a time' in this modelling malarkey.

I am going to try, for the first time, uploading a photo of the arrangement so that people, as electrically dim as I, can follow it instead of all these words. But hopefully you experts have enough with the foregoing.

As I say I will do the same for the lathe in a new thread. BTW, I don't agree with those who say it's not a proper lathe. It can do the little things I want to do, no problem. It just whizzes too fast.that's all. Frightens the life out of me and I nearly ripped my hand off once and the picture on the packing shews a child using it!

HowardGWR

Re: multi 12v dc take off -is this OK?

Postby HowardGWR » Thu Nov 11, 2010 1:45 pm

Well that didn't work :( It said my photo was too big so I am trying again to make it smaller than 1mb. Anybody know how to do this?

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Tim V
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Re: multi 12v dc take off -is this OK?

Postby Tim V » Thu Nov 11, 2010 4:16 pm

The Unimat 1 only runs at one speed. I have the Model Engineer review in front of me (03/05/85 for those who are interested).

The Unimat is not a toy, and had quite a good write up - if used within its limits. Clearly it can't be used for turning rough cast iron castings (bad luck Howard), but for a lot of non ferrous work, it should be adequate. The reviewer also tried it on free cutting mild steel - it worked. What were you thinking of using it for?

It also can be converted into a precision vertical drill.

The most important thing with a small machine tool is to ensure the tools are sharp, otherwise power is lost in heat.

There was a suggestion in the article that a simple thyristor controller could be used. Four batteries fit into the base so that would be 6V. Any ideas anyone?
Tim V
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HowardGWR

Re: multi 12v dc take off -is this OK?

Postby HowardGWR » Thu Nov 11, 2010 9:33 pm

Right, back to my mini drill multi take off issue, here is a photo of the set up. I just want to put the two wires of the drill on the same output as already connected for the Compspeed. I;ve done it and it works but the green light on the Compspeed comes on when you run the drill -does that matter was the question?
scalefourquery test.jpg
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Re: multi 12v dc take off -is this OK?

Postby grovenor-2685 » Thu Nov 11, 2010 10:12 pm

I take it the wooden looking box with the white gadget on top is the transformer/rectifier and the orange wires supply the compspeed? Are you then connecting the drill to the same place as the orange wires?
So this is on the input to the Compspeed rather than the output?

Do you have any information on the Compspeed that says what the green light is supposed to show? If not you will need someone who has one. Its certainly not normal for a controller to be affected by other loads on its input unless its reacting to a reduction in voltage.

Personally I would not keep my drill and controller permanently connected in parallel, there is no need, is there? to operate both at the same time. Best to get a 2-way switch or plugs and sockets so you can siply choose which one is on.
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Paul Willis
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Re: multi 12v dc take off -is this OK?

Postby Paul Willis » Thu Nov 11, 2010 10:34 pm

thomascpre wrote:Right, back to my mini drill multi take off issue, here is a photo of the set up. I just want to put the two wires of the drill on the same output as already connected for the Compspeed. I;ve done it and it works but the green light on the Compspeed comes on when you run the drill -does that matter was the question?
scalefourquery test.jpg


Hi Howard,

I have no idea about the wiring of your drill, as sparks are not my thing at all. I was just wondering whether there was a Dutchman hiding in the background as it looks suspiciously like the diminutive "...tje" hiding off the side of your test track :-)

Flymo
(Ik spreek een beetje Nederlands...)
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Alan Turner
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Re: multi 12v dc take off -is this OK?

Postby Alan Turner » Fri Nov 12, 2010 12:09 pm

I suggest you buy a variable speed transformer specificaly made for the job. Try here: http://www.squirestools.com/11-07.pdf

Alan

HowardGWR

Re: multi 12v dc take off -is this OK?

Postby HowardGWR » Fri Nov 12, 2010 2:13 pm

Keith wrote:
I take it the wooden looking box with the white gadget on top is the transformer/rectifier and the orange wires supply the compspeed? Are you then connecting the drill to the same place as the orange wires?

It's brown plastic and is a Bachmann transformer and controller so it can control my drill's speed as well.. I just leave it full on when using the Compspeed to drive the engine, so that only the controls on the Compspeed are used for that function.

'So this is on the input to the Compspeed rather than the output?'

Well what's output one side is input..... but yes.

'Do you have any information on the Compspeed that says what the green light is supposed to show? If not you will need someone who has one. Its certainly not normal for a controller to be affected by other loads on its input unless its reacting to a reduction in voltage.

Yes, the green light just means everything is ticketty boo - if you get a short for instance, the red light will come on, that's all. I just could not understand why it did not come on when nothing was happening, even when I connected the drill wires, but then shone when I threw the drill switch (that's on the lead to the drill).

The reason thus, for doing what i wanted to do, is that i could use the Bachmann controller to give variable speed to my drill, but at the same time do what it otherwise does which is to deliver 12vDc to the Compspeed.


It's a question about parallel connections and whether there is any technical issue with doing that.

On the Dutch thing, I am the founder of SNAG. I left Dave Doe and friends behind when i returned to England in 1991. It was when i demonstrated my split axle compensated pannier engine at Den Bosch, when we English lit up the Dutch to new ideas and layouts such as Petherick, Exbridge Quay, Bodmin and Mike Sharman's extravaganza mixed gauge effort appeared. The thousands of Dutch modellers (it's their Warley) were sensationalised by it all.

After I returned I went back to armchair status and anyway i have never understood electrics, unfortunately.
Regards, Howard

HowardGWR

Re: multi 12v dc take off -is this OK?

Postby HowardGWR » Fri Nov 12, 2010 2:52 pm

Alan Turner wrote
Try here: http://www.squirestools.com/11-07.pdf

Is this the 82012 or the MX82020 to which you are referring Alan? £30 or £50 sheesh! :-)

If you read my last, as long as my basic query could be answered favourably, I need not spend any money at all (see remarks about my Dutch background to explain the above reaction) but many thanks for the link.

Incidentally do you see that they sell the Unimat 1? Good to know that, as I was looking for a spares supplier, so thank you. Regards, Howard

So is there any technical problem in running two 12v outputs from a single 12v feed? This is where i am still ignorant


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