Advice on Trim Routers needed

[Tisr]

Hi guys

I'm setting out to build my first cnc machine - a solsylva 25 x 25 router. My intention is to use it for building composite r/c sailplanes. Initially I will be using it to cut templates from phenolic (ie 2D), but would later like to step up to cutting fuselage and other molds from MDF as well as wings and tail surfaces from high density styrofoam.

My plan is to use a laminate router as the spindle, but I'm beginning to find that the choices in a Australia are somewhat limited (as is my budget ). I had thought to buy a cheap maktec trim router, because I had been impressed with the quality of some of their other tools but I'm concerned about the lack of speed control. What can you guys suggest as an economical solution? Is it possible to add an after market PWM speed control externally or should I perhaps look at something like a bosch colt from the States? I'm going to be using the HobbyCNC board and steppers.

Any thoughts????

Kind regards

Dan

[Blu_Rock]

Dan, a popular entry-point choice appears to be the little Ozito router sold a Bunnings for about A$50. Check out the numerous threads at Woodworkforums CNC Section and in particular this thread. If you have a bit more cash to throw around, it may be better to go straight with a quality die grinder or even a spindle as discussed on this thread. A search on woodworkforum will throw up other discussions on routers/die grinders/spindles suitable for CNC applications.

I have haven't begun building my first CNC machine yet, but have the HobbyCNC 3 axis kit on had (luckily I bought it before the A$ dived) when I get around to it.. too many other projects on the hop at the moment.

Keep us posted (with pictures) on the progress of your build.

[Tisr]

Blurock, thankyou for the advice. Given the disposable nature of the ozito routers, I'd probably still lean towards the maktec a bit. I was surfing this morning and came up with this article on building a speed controller from Silicone Chip http://www.siliconchip.com.au/cms/A_111129/article.html.

Do you guys think this would work?

Kind regards

Dan

[Blu_Rock]

Dan, While the controller is designed for brushed 240VAC motors, note the warning ...

Some power tools and appliances don’t run smoothly at very low speeds when run from this type of phase control circuit. They sometimes display a behaviour known as “cogging” whereby they run in short bursts.

So the practical minimum speed for any appliance motor depends on its freedom from cogging. This will depend on the design of the particular motor but in general we can state that the cheaper the appliance, the less likely it will run smoothly at very low speeds.

Another factor that limits the minimum speed at which an appliance can be run is that most universal motors have an inbuilt fan for cooling.

Below certain speeds that fan is largely ineffective, so there is no cooling at all.

so I suppose that there is a risk that the Maktec, running at slower speeds, could overheat. I would think that it depends on how slow you intended on running the unit.

Blu

[Reflow]

Hi Dan,

I think many of us have been down this path. My thoughts are below:

--While everyone always points at the Ozito as a cheap little unit I would steer clear. The quality is dismal even for the price. The unit I had came stock with terrible runout and sticking the clock gauge on the cutter showed me it ran far from true. Although I suspect the motor itself wasn't too bad, but the collet seemed very poorly made which was probably the cause.
--I had a look at the silicon chip speed controller. I discovered no one sells the kit anymore. So I'm guessing either some parts are no longer available or there was an issue with them.
--While a bit more expensive than the Maktec trimmer. There is a Bosch die grinder (GGS27c) with 1/4" collet and variable speed that goes for about $300. I'm using on of these and it has done a reasonable amount of work without issue. It is also significantly quieter than the Ozito.
--The Bosch Colt you mentioned looks good, with the spindle lock and quick release collet making things easier. But if you can't get a 240v the stepdown transformer is going to set you back a bit.

Best of luck, let us all know if you find something better!

--Scott

[Tisr]

Guys

Thankyou for both of your replies. I am really interested in this speed controller and actually have the complete article here at work. It's actually about the third reincarnation of this design and has only been released this month (Feb 09) - which I believe is why it is not listed in Jaycar's catalogue yet (although it does appear in their ad in this magazine). I'm hoping when I come home to OZ in a months time it will be available.

Reading the full article, it seems to be quite a good little unit, claiming to provide proper speed regulation via a triac and scr. The article claimed that the low speed problems would only occur when you were doing things like trying to use an electric drill as a screw driver. I don't want to run the router that slow - just turn it down a bit for doing plastics. As for cogging - we'll see. Again I hope it's only an issue at very low speeds...

Dan

[ClaudioG]

I and a few others have bought a Kress spindle. I bought from this guy

http://www.damencnc.com/damencnc.php...bfe2e5fefd514e

Excellent spindle with variable speed (~10K to 30K RPM), high quality german made, lots of collet sizes.

Read this thread for more info on spindles.

http://www.cnczone.com/forums/showth...hlight=spindle

Cheers,

Claudio