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removing speed control

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mick7029/06/2018 14:07:04
524 forum posts
38 photos

been offered a titan scrollsaw by mate.

it's cheapest one by screwfix.

problem he as with it is keeps speeding up and slowing down.

is there a way of removing the speed control on it.

only going to use it on thin stuff and wood.

can get pics later of controller dial on front.

Buffer29/06/2018 14:54:26
168 forum posts
46 photos
Does it have a belt to drive it. I thought my bandsaw motor was on the way out once but it was a ruined belt.
John Rudd29/06/2018 14:55:28
1396 forum posts
6 photos

Removing the speed control from the motor depends on the type of motor used.

If its a pemanent magnet motor, you will need to feed the motor with high voltage dc to get it to run ( high voltage means greater than 12v......) if its a universal motor, then simply connecting mains 240v ac will get it to run.....

If its an induction motor......well lets see what you come back with..with regards to the type of speed control thats fitted..

Speedy Builder529/06/2018 14:59:15
2107 forum posts
146 photos

Check belt and brushes, I can't see why the electronics would do that.

Neil Wyatt29/06/2018 17:09:51
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18237 forum posts
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Might be a dirty speed control pot?

mick7029/06/2018 17:34:57
524 forum posts
38 photos

right this is it.

pic of dial and plate on side.

when it speeds up almost shakes it self to death.

john fletcher 129/06/2018 17:52:09
623 forum posts

Having seen the picture I think Neil is correct. If you unplug the saw, then open up the box with the knob on the front and you will see what looks like a volume control and on the back of it (if you are lucky) will be its value in Ohms. For example 10K Lin. You can buy a replacement from several suppliers on line RS, Farnell, Rapid or ESR., it must be a Linear type (Lin ) Or, if you know of an electronic repairer a quirt with their RS switch cleaner might solve your problem. John

mick7029/06/2018 18:06:43
524 forum posts
38 photos

apparently been like it from new

Ian Parkin29/06/2018 18:15:39
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839 forum posts
202 photos

bear this in mind if you want it flat out all the time

All these cheap scroll saws i have seen vibrate like mad..very poorly constructed and balanced they need fastening onto a thick felt cushion

Brian Sweeting29/06/2018 22:07:03
443 forum posts
1 photos

Shaking itself to death is a known effect of running these models according to lots of various forums; speed control probably fine.

I.M. OUTAHERE30/06/2018 08:23:23
1468 forum posts
3 photos
Posted by john fletcher 1 on 29/06/2018 17:52:09:

Having seen the picture I think Neil is correct. If you unplug the saw, then open up the box with the knob on the front and you will see what looks like a volume control and on the back of it (if you are lucky) will be its value in Ohms. For example 10K Lin. You can buy a replacement from several suppliers on line RS, Farnell, Rapid or ESR., it must be a Linear type (Lin ) Or, if you know of an electronic repairer a quirt with their RS switch cleaner might solve your problem. John

Some pots have lin or log printed on them some have an A for analogue or a B for linear .

Does the speed keep changing with any sort of regularity or settle down after a few minutes ?

You really do want to keep the speed control function on the saw as it makes them more usable , sometimes you want to slow things down for delicate work etc .

It could as neil suggested be a crook pot or it could be a crook connection or dry solder joint , the only way to check it is to pull it apart and have a look .

Edited By XD 351 on 30/06/2018 08:24:36

mick7030/06/2018 08:50:09
524 forum posts
38 photos

nothing on back of controller

couple of pics if any use.

it starts of slow then speeds up and slows down and sppeds up at random.

Clive India30/06/2018 09:43:53
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213 forum posts

I think it is unlikely to be the pot (potentiometer) but if you want to test it...

The speed pot has 3 connections. Disconnect the middle connection (black) and connect it to one of the other pot terminals (also connected to red wire) and run it - you should get either max or min speed depending on which end.

Then do the same but connect to the other pot terminal (also connected to blue wire) and run it again.

Leave red and blue connected to the pot at all times.

This will give you max and minimum speeds. If still not stable in speed it is 99.9% certain not the pot. If it is stable then change the pot - the value is written on it and plenty on ebay.

Edited By Clive India on 30/06/2018 09:52:51

Neil Wyatt30/06/2018 17:23:05
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18237 forum posts
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I see one of the preset pots on the circuit board is marked 'min'. I guess the other is marked 'max'.

Bearing in mind that board has mains on it, experimenting with careful adjustment when the thing is unplugged should enable you to set sensible top and bottom speeds.

Beware of setting the slowest speed too slow, or it will overheat.

SillyOldDuffer30/06/2018 17:55:23
Moderator
6330 forum posts
1389 photos

Misbehaviour when the board is vibrated suggests a loose connection or bad joint. For example an intermittent on the either of the max or min pots would cause the control range to float and confuse the poor thing.

Try flipping the board over and checking with a magnifying glass for dry joints, cracks between joints and board or components and - less likely - tiny whiskers of solder bridging any connections. This link has a good overview.

larry phelan 130/06/2018 18:05:27
825 forum posts
17 photos

I bought one of those scroll saws many moons ago,never did get any good from it,could never see eye-to-eye with it,at the end,could not be bothered with it,and dumped it.

Perhaps being more used to a 12" bench saw did not help,but yes,I did find that they jump all over the place [one of the reasons I did not see eye-to-eye with it. They are OK if you want something to play with,but for serious work ???

mick7030/06/2018 18:22:38
524 forum posts
38 photos
Posted by Neil Wyatt on 30/06/2018 17:23:05:

I see one of the preset pots on the circuit board is marked 'min'. I guess the other is marked 'max'.

Bearing in mind that board has mains on it, experimenting with careful adjustment when the thing is unplugged should enable you to set sensible top and bottom speeds.

Beware of setting the slowest speed too slow, or it will overheat.

cheers i set them so both same and runs lovely.

min was turned out two turns max only one.

set both to one turn.

mick7030/06/2018 18:25:35
524 forum posts
38 photos
Posted by larry phelan 1 on 30/06/2018 18:05:27:

I bought one of those scroll saws many moons ago,never did get any good from it,could never see eye-to-eye with it,at the end,could not be bothered with it,and dumped it.

Perhaps being more used to a 12" bench saw did not help,but yes,I did find that they jump all over the place [one of the reasons I did not see eye-to-eye with it. They are OK if you want something to play with,but for serious work ???

only going to be used on thin stuff for kids and cutting wood discs for kids to do pyrography on.

Michael Gilligan30/06/2018 18:34:48
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16389 forum posts
715 photos
Posted by mick70 on 30/06/2018 18:22:38:
Posted by Neil Wyatt on 30/06/2018 17:23:05:

I see one of the preset pots on the circuit board is marked 'min'. I guess the other is marked 'max'.

[ ... ]

cheers i set them so both same and runs lovely.

min was turned out two turns max only one.

set both to one turn.

.

Great result yes

MichaelG.

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