CNC Wax Bell
Yes! It can be done, as if there was any doubt.
I started with a 2″ diameter 3″ long wax cylinder. On the Taig micro lathe I turned half the length down to just over 1″ (not critical) so it could be held in the self centering 4 jaw chuck shown here. Once in this chuck it was never removed until finished.
I machined the inside on the Taig CNC mill as a 3D pocket. Then I switched to the 4 axis setup and ran the outside profile. When finished is shown in the first picture. Note the smooth finish that is possible.
Then I went back to the lathe (still in the original chuck) and turned down the stem and top of the bell. It would have been too weak if I had done this earlier. The big end will be cut off before spruing for the cast.
Not bad for a first try but still a lot of things to tweak.
The next bell I will spend more time on the CNC picture taking. I’ll do some video of the machining action. There was quite a pile of wax chips and turning ribbons. That green wax is a joy to machine. The bottom three pictures shown are more fitting I suppose for the lost wax casting over in “Ramblin’ Dan’s Workshop” than here in the machine shop blog but to get to this point there was a whole heck of a lot of CNC machining and some manual lathe work.
Bells and CNC Thoughts
I have found a niche for my casting and CNC machining desires. It is the designing and creating small custom bells to be cast in silver, brass and bronze; also using bell metal if I can find or make it. Bell metal is high tin content brass.
I am currently working on obtaining the correct wax for CNC detail machining of the designs. My two Taig mills, one of which set up for fourth axis millings are perfect for the size of bells I am considering. That is, bells with a diameter between one and two inches at the open end. I figure they may be one to two times the diameter in height for the bell section. Then whatever is used as the handle or bell mount.
I will pocket mill the bell interior from the end of the wax cylinder, probably using a ball end 2 flute tool. Tool size will depend on the bell diameter and depth. Perhaps 0.250″ on larger size bells down to 0.125″ on small bells. No interior details, just hollow out. The 2nd set-up to do the exterior will be milled on 4th axis rotary, roughed with perhaps 0.25” ball end before details. As far as the detailing I have used as small as 0.003 tapered wax milling bits Like an engraving bit (many hours of run time) making medallions. That is probably not typical for my bell project but could be the extreme. Most likely I will use 0.010-0.020 mill end sizes. I buy my wax bits from Bits&Bits and they are especially made for detailed wax carving, spiral open flutes, etc. Initial trial runs will not be detailed. Just get something basic to carve then cast and see results.
I am thinking this is a perfect combination of my skills and… Continue reading
Flight of Fancy
I had a long hiatus (about four weeks paid time off) away from my regular employment, creating time to take a good long at the route I should be heading with my at-home workshop activities. What I do for the rest of my life should be something I really enjoy. I have been making small wax carvings by hand and machine.
I have come to a personal decision about my capabilities in creating precision miniature wax carvings. The results of my experiments have shown that even with my PN, I am capable of detailed hand carving but not in the speed and degree of accuracy that I would like to perform. I suppose that is because I have spent most of my life being very accurate with dimensions and machine tools and maybe six months wax carving by hand. Duh?
My plan at this point is that I am going to continue putting effort into perfecting my CAD/CAM creative effort but not abandoning the hand work. I have discovered both to be very enjoyable. To those of you who follow my “in the shop” ramblings about machines and machine software, you will see that machine carving will continue.
Everything I do in my CNC interests is scalable. That means the effort and skills to do small scale carvings are the same whether one inch high or twenty four inches high. The size of the tool bits and the machine just change.
I am totally blown away by what I can do with small machines and tiny milling bits. This is where I have spent most of my time and money. I presently have what I need as far as the machines capable of doing the detailed work. I will be writing a lot more about how they work and how… Continue reading
Miniature Machining in Wax
I occasionally struggle deciding where I should post the project I am working on. I try to keep this blog on track by sticking to subjects regarding machining. Then there are projects that involve machining but include a lot of other skills as well.
I started a web site and blog for those non-machining projects called The Hobbyist Workshop (THWs). It is linked in the sidebar in this blog. The dilemma is where to post.
Here is a link to the recent machining I did last weekend and posted in THWs. Making a Medallion. It is pure machining but the next step is rubber mold making and casting in pewter. The new mold looks great buy the way. I hope it works as good as it looks.
I have made quite a few attempts at this project and blogged on it several times and even made a video (below) of an earlier attempt, but it is not ready for a major article. The machining is fine. It’s the mold making. I call it a learning experience. I am getting a lot of practice time.
There is no wax material guide in the tool but there is two kinds of plastic listed, both hard and soft. At first I thought soft would be good but as I thought about how wax actually mills, it acts like a hard plastic with the type of chips it makes. Soft plastics kind of gum up and take special consideration in my limited experience with them.
So I picked the hard plastic and started plugging in the numbers for the Taig mill and the cutting tools I am using. I used a 1/8 ball mill for roughing and a 1/16 ball mill for finish.
I was pleased to see there would be no problem running the rough at full speed (for me that’s 50 IPM) at 20% step. I am sure it could go faster. The spindle RPM on the Taig was 10,600. BTW it will run all day at that speed.
The chips were wonderful and very clean. I use a continuous air blast to keep the chips clear and the tool and wax cool.
My next goal was to get an excellent finish with as little bench work as possible. The GWizard figured out a 0.002” step over which is about 3.2% and a 20 IPM feed again at 10,600 RPM. It took me (the machine) two hours to run the finish pass in the picture.
With the air blast I never saw the chips in the finish pass. Just a very clean smooth area growing slowly as it worked 90 degrees to the roughing pass. I had left 0.020” for the… Continue reading