Thread: Delta saw starts too quick

You could use one of the electronics kit motor speed controller units with a universal motor provided that you are prepared to wind the speed up and down manually.

I am not aware of any that include a soft start feature but it should be possible to modify the control system by substituting the control pot with a resistor/capacitor combination and a relay to discharge the capacitor to provide the low speed starting and steady acceleration over a couple of seconds.

The other option would be to roach the soft start module from some cheapish tool that is equipped with one as standard. An obvious donor would be a 9in angle grinder, which normally use a 2000W motor. Aldi have these occasionally for about $60.

Whatever you use connects between the power switch and the motor, as it needs to sense when the power is removed to initiate a start cycle when you turn it on.

Thanks Malb, that gives me a few options. When you refer to the electronic kits, are you talking about the types that Jaycar etc sell?
Thanks.

That was where I started thinking, googled up the Silicon Chip article for the more recent one hoping to get a squiz at the circuit, but the online version didn't extend that far.

As I suggested it should not be too hard to incorporate an resistor capacitor and relay network to give a slow start function. The concept is that the relay contacts short out the capacitor and shut down the output when the motor poweris off. Once the power is switched on, the relay contacts open allowing the capacitor to charge through the resistor over a couple of seconds. As the capacitor voltage increases, the unit increases the motor speed. You would need a low power transformer and rectifier system connected accross the mains after the power switch to activate the relay.

From every point of view (simplicity, safety, sustainability) I would be looking at a bigger belt or doubling the belt. Either that or something is wrong. Delta saws are not carp and this should not be happening regularly IMO, unless there was a bad model etc. I can see sawing problems under heavy loads even if you have a soft start.

Are you sure it has not been modified to slow the blade (I have no idea why!) with a small drive pulley or something?

Dunno

Nick

Nick, it is not possible that someone has modified the pulley setup. The small pulley has the teeth machined into the motor shaft. The motor armature and the blade arbour are in the same housing and this whole housing moves in the trunnions.A diagram of the setup can be seen here. These are a very unusual designed saw and this model may be the only one with this setup.

AFAICS there is a separate pulley (PN 225) but it looks very proprietary. I think I can see what you mean. The housing is cut away for the belt. But that is outside the motor main bearings and the housing is "false". That makes a larger driving pulley tough to fit, unless there is a big gap between the housing and the belt as it is ATM. The pulley does look separate though, to me. There is no way to tell how many teeth it has, or what diameter.

Now this complicates matters! I thought I may trawl about to see if anyone else had the problem with this saw....and there is a version out there that is direct drive, still called the 36-600.
Delta 36-600 parts breakdown on ToolPartsDirect.com
So I can't even tell which model is being written about elsewhere, to see if the belt problem is common.

Whether your model was a problem and they remodelled it, or what, I am not sure. Most of the posts I found were your own attempts to do what I am now trying to do: see if this was just a "problem". Seems it may well be.

However I now understand that both were driven by a universal motor and these are very simple to control, as Malb suggested, even using something out of a powerful 9" grinder or hand drill (I have a Ryobi drill that is 2400 watts!)

I don't know what your electric kit / building skills are, but the Silicon Chip article is only $8.80 to buy online. I do not know if a circuit board and/or kit is available for sale though. Also, that circuit is 10A and your saw is 15A _Theoretically_ that just involves different SCR's at the big end of the circuit. But here you again will need to know what you are looking for and do some research.

A pre-built, plugin version of this would be fairly $$.l

Malb's idea of a simple auto control system for the motor speed controller for "soft start" sounds good. It's that or use the MSC then wind it up with a knob each time.

Remember that this is 240Volt! It is also high current. You would need to understand heat sinking etc, unless this is laid out very well in the article. And even then yolu are looking to up the current.

My honest opinion is that to do electronic speed control is a "project" unless you are pretty savvy. Whether you like or can justify such a project .....?

In one of your threads, somebody mentioned using a Link-Belt. I am a bit rusty on those, but they are the bee's knees for tough grip and vibration prevention. Whether they would fit your pulleys or not....

I am finding this frustrating on your behalf..

Nick

Electronic speed control sounds like the best solution but I'm not qualified to give advise on that.

If that can't be done is it possible to change both pulleys? Making them larger would spread the load over more teeth and as long as the ratio of the circumferences stays the same then the speed will stay the same.

Or as Realold nick says, doubling the number of belts

hmmm....you did not hear this from me, as it may well be illegal and if not done right (as with all this) could be dangerous.....

series resistor anyone? A motor speed controller may be more than is needed. While the saw would probably eventually reach almost the same speed as without, it would have a lot less torque and this would soften the startup, when the blade has to be accelerated. When up to speed, short the resistor with a switch. That could be based on a manual switch, timed switch, and even a switch that de-latches when the power is removed. The resistor would have to be able to take the power that the line voltage gave it. A high powered (500W?) shop lamp in series would be a start and the beauty there is that even though it will get hot it is designed to do just that, safely. Trouble with a lamp is that they hate being switched on and off all the time. But I suppose this would not be happening 100 times a day. The possible trouble here is that if you have too much series resistance, the saw will not get up at all.

Any thoughts anyone?

Unfortunately cow, changing the pulleys is not an option. The pulley that is the driver is machined into the armature shaft, not fitted on to it. The second reason is there is no centre distance adjustment, so if it was possible to change the pulleys, they would have to be perfectly matched to the belt length. Doubling the number of belts is also not possible due to the design.
REALOldNick, I like your thinking because if it were to work, would be a very economical option. Might have to talk to the electricians at work to see what they can come up with for me, as my knowledge when it comes to electronics is virtually zilch.

Good luck and let's know what happens. I hate it when something just starts to get all out of proportion.

The leckies may balk at the idea, but I have seen similar ideas in the past.