# Using a CNC "mill" (not exactly) to recreate a plastic dial face



## Mike6158 (Oct 5, 2019)

One of my upcoming radio repair projects is an Arvine Model 61 tombstone radio. Vintage 1935-1936. I need to recreate these, they are the only thing stopping progress (other than time):












The dials were "peened" (for lack of a better word) on to the dial dial hubs. I had the idea to remake the dial hubs on my mini-lathe and I got as far as making a prototype. I don't have a mill and the design calls for 4-40 or smaller screws to hold the dial on the hub. 

I think I can create the hubs or, worst case, try to use the old hubs. At this point the hubs aren't the issue, it's the dial faces. If I could find a way to mill the lettering and dial marks into the plastic I could fill it with clockmakers dial wax. It works good on metal but I'm not convinced that it'll work for plastic. The light in the radio shines thru the dial so it has to be transparent material. I made the hubs in Fusion 360 but I never could get a straight answer from anyone on whether or not I could import the 1:1 high res scans of the dials and use that to create what I need. 

*Is something like this a good idea for cutting out and etching lettering?* https://www.amazon.com/SainSmart-Ge...jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==

I don't have an opinion about this brand one way or another other than at 7" depth it's a little small. It's got good reviews but Amazon reviews are hit or miss. 

Just FYI - Here's the Fusion 360 rendering for both hubs -

Large dial






Small dial


----------



## RJSakowski (Oct 5, 2019)

The dial with the frequencies would be hard to do with engraving.  I would look at a photo process.  You can recreate a dial in Fusion 360 and print it onto a transparency using a laser printer.  The laser printer is preferred over an inkjet as the printing is more durable.   You could bond the transparency to a piece of appropriately colored transparent plastic.  I would do so from the rear so the artwork is protected.  

Another approach would be to use a process like this. https://decalprofx.com/index.html

A third process would be to use a CNC diode laser to burn the artwork into the plastic directly.  You should be able to fill the burned artwork with a black paint to create your dial.  Blue or UV lasers in the 2 -5 watt class are available for less than $100.  BangGood sells complete laser engraving packages for a little over a $100. eBay has yellow acrylic in 1/16" thickness.


----------



## Mike6158 (Oct 5, 2019)

On the upside the original dial was clear (but I'd probably go for slightly tinted). The original thickness is 1/32".

I'm not very good with Fusion 360. I made a few attempts at creating the dial and failed. The dial scale isn't linear (but I'll bet you already knew that). 

I like the decal process and the idea of just using a photo process. 

Cutting the holes will be a challenge. The first dial (in this post) has a 1/2" ish center hole and a smile shaped cutout below the center hole. There's a third piece that isn't broken that has a similar, possibly the same, cut out so I may be able to get the dimension right on that.


----------



## RJSakowski (Oct 5, 2019)

Some time ago I had downloaded a couple of programs with which I was able to take satellite images from Google Earth and convert them ti vector line art.  The first took the raw image and converted it to a two color image.  The second converted that image to vector line art.  That line art could then be imported into a CAD program to create the dxf file.  I believe that the software was Algolab R2V Toolkit and Algolab PtVector.  Here is one of the images and the resultant dxf file.  The images are a 1 sq. mi. area west of Sioux Narrows on Lake of the Woods, Ontario, Canada.


----------



## Mike6158 (Oct 5, 2019)

Wow! That's a nice looking conversion. I work with a guy that does 3D CAD work. I don't know why I haven't talked to him about this. One of the tools that he has available is a very high res 3D scanner ($100k). It even picks up bugs flying overhead. Not useful for what I need but pretty cool device. I'll see if he has a way to convert my scans to something useful.


----------



## RJSakowski (Oct 6, 2019)

The software that I mentioned had a free 30 day trial period.  I never bought the paid versions (around 60$ for the pair).  About ten years later, I did a similar thing converting Chinese characters to vector format which I imported into SolidWorks  and created a CNC program. A full description is here: https://www.hobby-machinist.com/thr...in-your-shop-today.14637/page-115#post-298744  post#3444.


----------



## Mike6158 (Oct 6, 2019)

Wow, the plaque is gorgeous. I'm amazed at the number of lines of gcode for both operations.


----------

