Saturday, February 4, 2012

Shop closed for the day

I was kept out of the shop today though I've quite a few things to try out.  My little Ruth is having a fever that went off after medication but came back up a few hours later.  Her mommy was out to transport an elderly person to church and her elder sister, Alicia, was stuck with her activities on the Internet.
Ruth was crying when mommy left home.  So I distracted her with the 2 Mr Bean movies I bought last Sunday after church.  We had fun watching the silly fella.  When she was feeling better, she got restless and wanted to play.  So my right hand was transformed to a snake head attacking her while she fended herself laughing away.  She fell asleep when she got tired and drowsy from the medication. I fell asleep too, tired of being the snake...

If time permits, I'll do some work tomorrow.  Otherwise, it will be 2 weeks from now - we'll be going to my dad's factory in Malaysia next weekend.

I read about a gear making software today, written by Art Fenerty, the creator of Mach3.  From the videos I've been watching, it seems a good piece of software for me on learning how to make clocks, especially if it only cost USD75 for a license which I can use on both the computers I'm using for my CNC work.  I'll start with the demo to see if I'm up to using it.

As I think about it, the more I want to start building my first clock, the skeleton wall clock from W.R. Smith, in acrylic.  If I can put all the parts in my CadCam software, I can mill them out using CNC and put them together to form the clock.  I may be thinking too much about the likely problems I may encounter, like do I need a faster spindle with very small endmills and if the cut length of these small endmills long enough to cut through the thickness of the parts called for in the plan.  There is also concern about the speed and feed of the cut on acrylic, a material I've not tried playing with in the mill.  I don't have proper cooling to keep the endmill cool so that it wouldn't melt the material.  More research is required.

Anyone with experience in milling acrylic with smallish endmills, please chim in.  Kindly leave your name with your input so that credit can be given when I've the post up on the build.

I'm going back to check on Ruth with the thermometer.  Until the next session, be blessed.


Glenn said...

Hi Wong
I'm also looking at making clocks. Acrylic comes in two types, extruded and cast. Cast machines well even dry, lots of fine chips. I use a vacuum to keep ahead of the mess. I find extruded tends to be more gummy. I use a Taig mill and run the spindle at 10,000 rpm. Cutters range from .125 in to .032 in. I don't have a good feel for speeds and feed, I just tend to be convertive. has plans in electronic form and there in metric. I have experimented with the free DXF sample Brian provides. The size was to big for the Taig so I scaled it down in my cad program, seemed to work out ok. I can also recommend getting plans that match how you mill is setup. My Taig is setup for inches and while I can make it do metric it is extra step all the way along. One thing is pay close attention to drilling the center hole and cutting the teeth, I didn't on one of the gears and it was slightly off center. The one that was good I mounted the blank, drilled the center hole and cut the teeth without removing the blank from the mill.
Have Fun

Wongster said...

Hi Glen,

Thanks for the tips. I'll look out for cast acrylic.

I was playing with Gearotic Motion's 4th axis Gcode. When loaded into Mach 3, I see strange tool path on the screen.

I tried generating toolpath in BobCad cut the gear without RT. Only 0.5mm dia endmill can get between the teeth. Will that size break on contact on brass or acrylic?


Wongster said...

Sorry Glenn. Missed the 'n' in your name. Was replying using the iPhone... apologies...


Glenn said...

I frequently us 1/32" (.81mm) end mill in aluminum,brass and plastic. No problem if I'm not careless. The smallest I've used is .7mm in plastic.
I used to just guess at speeds and feeds but am now starting to use GWizard.

From GWizard
.019"(.5mm) carbide end mill 4 flute
DOC .0043"
Cut width .019"
Feed 5.398 IPM
RPM 10600
Mill Stickout .125"
Mill bit Deflection .0001"

Don't know if it works.


Wongster said...

I tried to play around with GWizard but couldn't get anything meanful (GWizard gave some sort of message about not being able to reach ideal depth or something to that effect).

Maybe I set the tool stickout by too much. I was just testing different numbers without measuring from the actual tool. Time to move my butt... lolz...

One question if you don't mind. I read somewhere that the epicyclodial tooth form has different pressure angle than those involute. Any idea what's the angle?


GeneK said...

Wong, I have been using Gearotic for quite awhile and always keep running into the small end mill problem. I'm planning to try using slitting saw blades with the spindle horizpntal. That should get around the fragility of small end mills.


Wongster said...


I'm likely to go with an epicyclodial (or is it epicycloidal?) cutter if I'm going ahead with this project at this moment.

A friend from the Sherline list advice me to learn the basic first before making clocks by making stuff that don't need high accuracy. He has a point. I've been jumping around a fair bit. I find it fun and fulfilling to be able to make something that people can understand and appreciate. Am not creative enough to do decorative stuff so thought of making a clock.