Warco WM 16 motor

Does anyone have any experience of replacing the standard 750w motor in the WM 16.

I'm now on my second motor but have a constant problem with overheating - which leads to the brush covers melting and jamming in body of the motor.

First motor was exactly the same and I've had to resort to breaking the plastic covers out and using plastic plugs and cable ties to hold the brushes in place.

Is there a similar sized slightly more powerful electric motor available that could be substituted?

I suspect that if you are running the motor at much reduced speed, its cooling is insufficient - especially if worked hard.

A fault of these cheaper machines. You might also find that the motor has a lower output power than you think.

As you said in another post you had stripped 4 gears in 12months I wonder if you may also be taking too heavy a cut with a hobby machine.

By installing upgraded gears you have removed the weakest link from the train, now you don't have a sacrificial gear to protect the motor from overload.

Edited By JasonB on 07/11/2021 18:31:52

It may be worth, after a hard cut, just letting the motor run at full speed, off load, to give it a chance to cool down, before the next hard cut.

These are hobby machines, so will not withstand the continual five or six 8 hour days hard labour expected of an industrial machine.

The Cincinatti vertical mills in the Training School weighed about 2 tons, and had 5 hp motors, so a 3/16" (4 mm ) cut with an 11" / minute feed was within their capabilities..

Our 150 Kg, 3/4 hp machines are not in the same league, and so have to be treated differently.

A bit of high speed no lad running will allow the heat to be dissipated between bouts of hard (for a hobby machine ) work,

Howard

No idea on that particular machine but I swapped the motor and control board on my Chester mini mill for a 3ph motor and cheap VFD for about the same price as a replacement motor. Never looked back it's far better than the original set up, standard motor used to get too hot to touch in about an hour, new set up will run all day. Lower power than yours but the motor came from inverter drive supermarket I think for about £50 and the VFD from a source unmentionable on here for a similar price, probably a death trap and not approved but it's worked fine and I am still alive! Best mod I ever did to it!

Paul.

Ian, what motor speeds and cutters do you normally use?

The nylon gears are still sacrificial gears and are still the "weakest link" in the drive train.

As many users of these machines will testify, it doesn't take much to strip the stock plastic gears. Like Iain, I was stripping gears regularly until I "upgraded" to nylon - usually during flycutting operations.

These Warco (and all the other variations of this machine) mills have a plastic hi/lo gear as well as a plastic drive gear, meaning that there are two "weak links" in the drive train - which is overkill and more to do with cost cutting than protection.

There's no need for the hi/lo gear to be plastic (or even nylon) and I use a brass hi/lo gear as the nylon drive gear will still "fail" first if required.

The nylon gears are used by a great number of users of these machines and they still allow more "sacrificial" safety than is necessary, as although stronger (and less likely to melt) than the soft grey delrin (or similar) gears installed in the machine, they will still "fail" when necessary.

How much work can be got out of a hobby mill before it overheats or strips gears? Good question! Two different problems:

• gears are more likely to strip under shock loads, as when a speeding cutter crashes into something solid. The motor could be running within specification when the crash happens, and the gear breaks to protect the drive train and to limit the heavy current pulse pulled by a stalled motor.
• Motors deliver more their rated power when the user overloads them. Plastic gears are unlikely to strip under a steady overload, but the motor will overheat. The gear isn't useful as a fuse and if the user persists, insulation, brushes and electronics are all likely to be damaged.

Therefore the operator should avoid crash-bang cutting, and back off when that type of cut is unavoidable - adjust RPM, depth-of-cut and feed-rate to minimise the risk of damage.

To get a feel for how heavily a particular motor is loaded by the operator, I suggest measuring the input with a cheap wattmeter (example of type here). Note how much power is consumed when idling, and how much during a normal-to-you cut. The motor is working to full capacity If the wattmeter registers motor rating + 10%. And the motor is overloading if the wattmeter registers more than that. Overload is a silent killer; the operator may not know anything is wrong until the motor fails outright, or the dreaded magic smoke appears!

Hobby motors are unlikely to be rated for continuous output at full-power. As a result they gradually overheat unless a busy operator pauses to let them cool down. Not a problem in my workshop because I rarely remove lots of metal in one go, and spend ages resetting work and thinking. However, when I do a lot of work on a large lump of difficult metal, I run the motor for 10 minutes, then let it cool for 10 minutes, and repeat the cycle until finished. If the motor is accessible, check how hot it is with the back of your hand: give it a rest if the case is uncomfortably hot. If an owner often finds his machine gets hot, he needs a bigger machine! If that's not possible, take more time.

There's a reason Industrial Machines cost 6 to 20 twenty times more than hobby kit. They're very substantially beefed-up to slog through production work. We have to remember hobby machines are comparatively delicate.

I don't know if the plastic gears in these machines are fuses or cost-cutting. Possibly neither! Another common reason for using plastic gears is they are much quieter. Only the designer and production engineer would know for sure, the rest of us are just guessing...

Dave

Dave, as William points out, they are not there as a ‘fuse’. Otherwise it would only require one part to be a point of failure.

Noise may be a factor, but I suspect it comes down to cost as the main reason (as usual?).

These parts don’t seem to be so easily accessed to replace. A modern fuse is simply ‘remove and replace’ from an accessible location.

It also seems like fly-cutting may be something that stresses these gears? That may be partly down to the operator as well - expecting cuts across the piece at as near perpendicular to the edges as possible. Whenever I fly cut (not often) I like to set the workpiece and cutter such that the cutter starts cutting at a shallow angle (and may leave nearer perpendicular). It certainly needs the tramming spot on, or the item may measure differently on each side (instead of low in the centre🙂 ).

If only there was a temperature trip on these motors, it would avoid many failures. Again a cost cutting exercise? A thermal fuse costs pennies, but a cooked motor cost a lot of £p.

I don't think it helps motor life much by putting the motor in a metal box with very little ventilation. It may help cool the motor to remove the louvres from one side of the motor enclosure and fit a 120mm computer fan to draw air through and around the motor.

John

At least you can say the control board is as tough as nails.

I'd love to see a photo of the chips that machine produces.

Best not generalise too much, my X3 just trips the electronic protection and simply needs a flick of the switch and it's up and running again. I think it senses current not temp as otherwise you would need to wait while it cools down

Oh and it's not enclosed either.

Agreed, but replacing a thermal fuse at regular intervals would likely have one of two outcomes.

1) The operator would learn to operate with a little more care - and consideration for the machine, or

2) The operator would fit a higher rated fuse, carry on overloading the machine and eventually fry the motor.

Your Sieg machine may trip safely, but there are a lot of machines out there that apparently have not….

My VFDs have an upper current limit and trip if overloaded. Nothing unusual, but I can gauge how loaded my lathe motor is and alter the depth/feed accordingly. Also the speed can be altered mechanically on the move, while the motor is running at constant speed (like at full power!).

My small mill is the same and t’other mill has a 6 speed gearbox, as well as the possibilty to modulate the motor

All ‘old hat’ vintage British machines still working very well, even though 60-70 years old.🙂

The remaining ones are. How many were used up doing the jobs they were bought for?

75%

There's a need for unburstable piecework machines out there.

Edited By Dave Halford on 08/11/2021 19:25:15

A 60-70 year old m/c will be worn out, much like a 60-70 year old human.

Tony

They both persist in still working too

Hi Ian,

I have a similar mill, a Chinese "Optimum BF20LB" mill. I've repaired the motor on several occasions ! I made and replaced the gears with steel ones because the plastic ones stripped the teeth, and it was more cost effective to replace them. Actually the gears stripped whilst using a slitting saw on aluminium, the work got hot and grabbed the blade stripping the teeth off the gears.

I do have a 3 phase motor to replace the DC one and have made some parts to mount it, however a ducted cooling fan mounted on top of the existing motor seems to have much reduced the heat that is created. The major problem with the heating of the motor is simply that the only way that the armature can get rid of the heat is through the bearings. There are no field coils to conduct the heat into the motor body !

The brushes and brush holders suffer badly because of it. Also the push on tags don't make a good electrical connection so they get hot and the resistance increases causing them to get even hotter. I've thoroughly cleaned and soldered the tags to the brush holder terminals. This removes the major cause of brush holder failure due to heating.

The motor still gets very warm but nowhere near as much.

Edited By John Baron on 08/11/2021 19:50:36

Posted by Tony Pratt 1 on 08/11/2021 19:31:25:

A 60-70 year old m/c will be worn out, much like a 60-70 year old human.

Tony

I have a 1966 Bantam but don't consider it to be anywhere close to worn out and I don't suppose another 10 years of hobby use will make much difference, it was bought from a College when they were clearing out the department around 1980.

I guess if had been used in an industrial nature it would perhaps show more signs of wear, that would be dependent on the frequency of maintenance provided by the user.

Emgee

I have a Champion V20 mill, same configuration as the WM 16 with the motor inside a poorly ventilated shroud, had overheating problems when driving the mill hard during warm summer weather, smelt very hot. Solved the problem by fitting two small computer fans into the front of the motor shroud, driven by a 12 volt led power supply, the fans come on whenever the mill is switched on for use. The two computer fans can shift a fair volume of air and since fitting there have been no overheating episodes. Dave W