Suggestions for spindle replacement on Hobby CNC Gantry router

[DMBGO]

Hi all, about 12 months ago I built a hobby CNC gantry router, which uses a dremel as the spindle. I spent a lot of time building it, but was rather dissapointed with its performance, due to what I see as weaknesses in the design of the Z axis. The dremel mounts in a plastic holder, which is a Dremel accessory, but the holder has quite a lot of flexure under load. In addition to this the Z axis slide was difficult to make with any degree of accuracy using the plans and method provided. Lastly the Dremel itself is really noisy!

After giving the whole thing a rest for a few months I have developed a new burst of enthusiam for CNC and I believe my machine could be fixed.
I have the following ideas:
1/ rebuild the Z axis using aluminium and silver steel rails instead of wood and perspex
2/ make a decent rigid spindle mount and replace the dremel with a quiet high speed motor, and fabricate a belt drive spindle.

I was wondering if anyone had any ideas as to what to use for a spindle motor, I'd like it to be quiet, light (since it is on the gantry and weight = inertia) not too big and to have a high speed that could be controlled electronically.

Am I dreaming?

[andy_ck87028]

My first thought is that performance should be the criteria for changing the dremel not noise. If the issue really is noise, then replacement with a high speed spindle may not cure the problem.

I would change the dremel to a high speed spindle for performance reasons only and irrespective would encase the router in a cabinet to cut the noise. (or turn the radio up)

I agree re. upgrading the dremel mount and changing the linear guides.

The main thing that has to be removed is flex...ie complete rigidity is the aim.

Given you are using a dremel, then I presume your machine is small and therefore you'd need lightweight materials for rigidity. Aluminium is possibly the best material to use.

Good luck

Andy

[CarveOne]

DMBGO,

The Dremel also has considerable flex in the shaft/shaft bearing/plastic case area that can't be corrected by a stiffer z-axis mount. It all adds up together into more than allowable flexing. You can make a stiffer mount but still have the plastic case flex problem. My Dremel hand operated router adapter accessory and plunge router accessory are barely useable with a new Dremel tool due to chatter in any relatively hard material like oak and plastics.

A trim router is a popular alternative to a Dremel tool. Harbor Freight used to have a cast metal case version of the orange plastic cased $20 trim router. Wish I had one of the discontinued metal cased models. I have the orange plastic cased model and will try it on a small cnc router at some point. It can be controlled by a 15amp router speed controller but will lose some torque in the lower speeds. It won't be much less noisy than the Dremel though. A Roto-Zip tool isn't quiet either.

I can't think of a quiet motor that will do the job unless it might be one of the brushless dc motors made for the large R/C model aircraft. They come in plain shaft or geared versions, and aren't cheap. I'm thinking something bigger than a Hacker C50 class motor. They will need a dc power supply of many amps to drive them. Might be worth looking into out of curiosity though.

CarveOne

[DMBGO]

Thanks for the replies Guys, you have given me a bit to think about. I will definitely look into the model Aplane motor option, as cost isn't really an issue if I can quieten it down. some of the engraving etc that I was doing with it, before I cracked a sad with the router, took hours and the shed was uninhabitable due to the banshee like wail of the Dremel. I wonder if its possible to quieten a dremel down?

[andy_ck87028]

build a sound proof box to put the CNC machine in or turn up the radio

[CarveOne]

Originally Posted by DMBGO Thanks for the replies Guys, you have given me a bit to think about. I will definitely look into the model Aplane motor option, as cost isn't really an issue if I can quieten it down. some of the engraving etc that I was doing with it, before I cracked a sad with the router, took hours and the shed was uninhabitable due to the banshee like wail of the Dremel. I wonder if its possible to quieten a dremel down?

You could record hours of Dremel "music" to hard drive, shift the noise phase 180 degrees, play it back through a high powered stereo system, and adjust the volume level increasingly higher until it gets quiet enough that you can hear the birds chirping outside the shop.... Or get a good hearing protector to wear while the Dremel is running. Can't think of much else at the moment.

CarveOne

[DMBGO]

Originally Posted by CarveOne You could record hours of Dremel "music" to hard drive, shift the noise phase 180 degrees, play it back through a high powered stereo system, and adjust the volume level increasingly higher until it gets quiet enough that you can hear the birds chirping outside the shop.... Or get a good hearing protector to wear while the Dremel is running. Can't think of much else at the moment. CarveOne

I didn't understand your reply, the mark 2 is nearly working - more soon

[CarveOne]

DMBGO,

My apologies for what now seems to be a flippant reply. There is a noise reduction technique that uses a noise source as amplified out of phase feedback to help reduce the original noise source level. Active noise suppression is commonly used in the newer hearing protection (ear muffs, etc.) for target shooters and factory workers. It can help with the kind of impulse noise that comes from a Dremel tool, yet it will let you hear a telephone ring, or someone talking to you. Active headsets sell for less than $20 USD from Harbor Freight. Peltor has the Tactical 6 model that is true stereo since each side has its own battery and volume control. These are made by many others at all kinds of prices and additional features such as built-in FM radio receiver.

CarveOne