router speed controller

[sunnybob]

anyone using an aftermarket speed controller on their router table?

I want to fit one to my makita, but there seems to be a mismatch on the specs.
The makita is an RP1800, which is apparently the wattage of the thing (3 1/2 HP)

The boxes available are rated for 8 amps (which appears to be good) but only 1500 watts (which seems to me to be very bad)

Any experience or technical know how?

 

[Trevanion]

I've got absolutely no personal experience of them or single-phase VFDs, but I've heard of these things burning out motors pretty quickly.

I did read your previous thread but I didn't catch what kind of bit you're actually trying to use, a panel raiser?

 

[MikeJhn]

I have been running a pump motor for about two years now with a VFD fitted at 35Hz this has reduced the output by about a third, but decreased the cost of running the pump by over 50%, a decent VFD can't be bought on the cheap if you want to go that route I could buy a couple of variable speed routers for the cost of the VFD.

 

[MikeJhn]

I want to fit one to my makita, but there seems to be a mismatch on the specs.
The makita is an RP1800, which is apparently the wattage of the thing (3 1/2 HP)

Bob there are 745 watts in one HP therefore 1800/745 = 2.4HP ?

 

[sploo]

anyone using an aftermarket speed controller on their router table?

I want to fit one to my makita, but there seems to be a mismatch on the specs.
The makita is an RP1800, which is apparently the wattage of the thing (3 1/2 HP)

The boxes available are rated for 8 amps (which appears to be good) but only 1500 watts (which seems to me to be very bad)

Any experience or technical know how?

Single phase routers do speed control by chopping the AC waveform (if I understand correctly), so assuming it's single phase I wouldn't advise using any form of VFD.

HP ratings on tools can often be optimistic (understatement). 3.5HP = 2600W, but even if the tool draws that then the output HP will be less due to the motor being less than 100% efficient.

Amps to Watts depends on the voltage, so if you're on a 230V supply then 8 amps should be good for 8x230=1840W.

Would it possibly be cheaper to buy a router with speed control rather than adding the speed control?

 

[MikeJhn]

"Single phase routers do speed control by chopping the AC waveform (if I understand correctly), so assuming it's single phase I wouldn't advise using any form of VFD."

Why would you need a VFD when you have a router that has a speed control, keep up Sploo. LOL

And if I understand these things Waveform is Frequency so a Variable Frequency Drive (VFD) is what they use (hammer) you poor thing, you seen very confused, mind you it is late. LOL

 

[sploo]

"Single phase routers do speed control by chopping the AC waveform (if I understand correctly), so assuming it's single phase I wouldn't advise using any form of VFD."

Why would you need a VFD when you have a router that has a speed control, keep up Sploo. LOL

Erm. You are joking right?

Bob has an RP1800. Which is single phase. And doesn't have a speed control. Single phase routers with speed control do it using AC chopping. Therefore I wouldn't advise using a VFD to do speed control on a single phase router that doesn't have speed control built in. Clear?

EDIT:

"And if I understand these things Waveform is Frequency so a Variable Frequency Drive (VFD) is what they use (hammer) you poor thing, you seen very confused, mind you it is late. LOL"

One of us is indeed confused Mike.

Routers (AFAIK) tend to use a TRIAC to chop the AC wave to reduce speed (part of the reason why they lose torque at lower speeds). It's also the reason for the existence of products such as the http://www.vhipe.com/product-private/SuperPID-Home.htm ; which are intended to be used instead of the TRIAC to vary the power (note: power, not frequency) to achieve a desired speed.

In general, it's a bad idea to use a VFD on single phase motors (e.g. https://www.maderelectricinc.com/blog/c ... hase-motor); though that article is likely referring to induction motors rather than the brushed/brushless motors found in hand held tools.

Any other LOLs to add?

 

[sploo]

Incidentally, if I read https://www.makitatools.com/products/details/RP1800 correctly (being the US site), it claims to be a 15 AMP router. 15 AMP on a US 120V mains supply is 1800W, or about 2.4HP. Surprise surprise the 3 1/4 HP claim is followed by the symbol of doom ( :mrgreen: ) *. Sure enough, later in the page "*Maximum horsepower".

In otherwords, that 3 1/4HP may well be the locked motor current, or some other BS marketing power measurement. Certainly you're unlikely to be able to draw the ~20A you'd be needing from an average US wall outlet.

 

[sunnybob]

Sploo.... hero of the hour =D> =D> =D> =D>

You have solved my problems.
I knew I did not want or need a VFD, but could not find an answer to the apparent mismatch of watts and amps.
In america these speed controllers are 15 amps, in the UK 8 amps. But the 8 amp controller stated 1500 w maximum.
I have tried to find online the spec of this router but it seems its no longer sold in the UK. I appear to have fallen foul of the different calculations between 110v and 230v and the marketing claims of makita
Now I can buy my speed controller with confidence.

Thank you. 8)

 

[Trainee neophyte]

I have been running a pump motor for about two years now with a VFD fitted at 35Hz this has reduced the output by about a third, but decreased the cost of running the pump by over 50%, a decent VFD can't be bought on the cheap if you want to go that route I could buy a couple of variable speed routers for the cost of the VFD.

I am definitely not an expert in the mystical esoteric knowledge of pump electronics, but (assuming it is a standard centrifugal pump), can you not get the same effect just by throttling the flow (in other words increasing the head by putting a partially closed valve in line)?

Much wizardry and mysticism is required, so I could well be wrong.

 

[sunnybob]

This is another cost versus benefit question. If the pump is now costing 50% less to run,but you are getting 30% less water through it, how long before you recoup the cost of the VFD? It must be a pretty big pump to get back that money in any sensible time frame.And if the reduced output was the desired result, why not just buy a smaller pump with lower running costs anyway? :shock:

Of course my router question has no relevance to costs, i just want to run larger bits safely. 8)

 

[Eric The Viking]

Hate to say this, Bob, but Sploo had it: get a more appropriate router.

One of the issues is efficiency. As you drop the speed so the efficiency goes down too. But you still need power to drive a big cutter (there is no magic in either its diameter or mass). Low efficiency means wasted power, which means heat in the router. So if you are planning a big session of raising panels, or whatever, you may well find the router starts smelling "scorchio", etc.

My T11 is intended to drive those big cutters, but even that smells of winding varnish after a while.

The only "right" electromechanical solution would be a mechanical gearbox, but punters want cheap. In most applications that's OK, but not when you want low speed and a lot of torque together, like this one. As an aside, it's a reason why pillar drills work well for big Forster bits: the gearbox means _more_ torque at slower speeds.

 

[sploo]

Sploo.... hero of the hour =D> =D> =D> =D>

You have solved my problems.
I knew I did not want or need a VFD, but could not find an answer to the apparent mismatch of watts and amps.
In america these speed controllers are 15 amps, in the UK 8 amps. But the 8 amp controller stated 1500 w maximum.
I have tried to find online the spec of this router but it seems its no longer sold in the UK. I appear to have fallen foul of the different calculations between 110v and 230v and the marketing claims of makita
Now I can buy my speed controller with confidence.

Thank you. 8)

Actually you really do want a VFD, as it'll reduce speed by dropping the frequency, but still provide the full AC wave, and therefore good torque. Unfortunately, doing that with a single phase motor can let the magic smoke escape, so it isn't a good idea. An electrically savvy mate once tried to explain it to me, but I still think "back EMF" is a position in the Karma Sutra :mrgreen:

Assuming the external speed controller you're referencing is just a TRIAC based unit (they're basically just beefy light switch dimmers) then it should be no worse than the speed control in a cheap router. I believe some better units are behaving more like the PID controller I referenced (i.e. monitoring rpm and adjusting the "chopping" duty cycle in order to maintain a constant speed under load).

As Erik notes; dropping the speed using AC chopping isn't ideal, so indeed a gearbox or pulley system for reduced rpm would be better (you also get torque amplification), but cost is an issue.

Unless that speed control unit is basically £50 though it might be worth looking into a new router. The Triton TRA001 is particularly good in a router table, and not crazy expensive.

Alternatively, find yourself an old 3 phase induction motor, get a VFD, maybe a pulley and belt to drive a spindle + ER collet and you'll have a very quiet and extremely strong spinner for those big router bits.

 

[Eric The Viking]

I still think "back EMF" is a position in the Karma Sutra

Stolen for future use*

By the way, Google "Selsyn" for an example of extreme VFD. But... that works only with multi-phase motors, AND the torque is pretty low at lower frequencies.

In the early 1980s, I worked in a few film dubbing theatres (in this context notably the ones in Television Centre's East Tower) that had Selsyn systems. The Selsyn room looked like something from a Star Trek movie or something to do with WWII submarines - motor-generator sets in pairs, all just to move 35mm film around in sync - probably the same or less power than needed for a panel-raiser bit in a router.

They were three-phase, and they couldn't run locked at variable speeds (but you could "inch" the theatre, one frame at a time). The Selsyn ensured they wouldn't drift out of sync, but the whole theatre (multiple tracks, each with a selsyn motor-generator pair) ran up to single speed forwards/reverse, or down to stationary. I don't think even double speed was available.

Later systems used pulse trains and shaft encoders, but Selsyn simply had electro-mechanical clutches on the sprocket wheel shafts. It did the job, but the 'leccy bill must have been enormous.**

E.
*No, not that use!
**It was said of 1970s Television Centre that it was the most inefficient factory in the world - thousands of workers, enough power in to light a medium-sized town, and the only output was two signals, one volt peak-to-peak...

 

[sploo]

I still think "back EMF" is a position in the Karma Sutra

Stolen for future use*

Not with the wife I hope

By the way, Google "Selsyn" for an example of extreme VFD. But... that works only with multi-phase motors, AND the torque is pretty low at lower frequencies.

Never seen one of those before. A sort of electro mechanical synch/signaller. Interesting

 

[MikeJhn]

I have been running a pump motor for about two years now with a VFD fitted at 35Hz this has reduced the output by about a third, but decreased the cost of running the pump by over 50%, a decent VFD can't be bought on the cheap if you want to go that route I could buy a couple of variable speed routers for the cost of the VFD.

I am definitely not an expert in the mystical esoteric knowledge of pump electronics, but (assuming it is a standard centrifugal pump), can you not get the same effect just by throttling the flow (in other words increasing the head by putting a partially closed valve in line)?

Much wizardry and mysticism is required, so I could well be wrong.

The point was to reduce the cost of running the pump whilst still keeping enough flow to perform it's function.

 

[sunnybob]

I've bought one for 14 quid.
It has two chances. If I dont report back its worked. If I come back with pictures of exploded makitas it hasnt.

with reference to all the above, I dont do any kind of production work. I make smallish objects and almost every piece is a one off, so overheating is unlikely to occur.

 

[sploo]

I've bought one for 14 quid.
It has two chances. If I dont report back its worked. If I come back with pictures of exploded makitas it hasnt.

with reference to all the above, I dont do any kind of production work. I make smallish objects and almost every piece is a one off, so overheating is unlikely to occur.

If you don't report back then I'll assume the Makita exploded on Bob