This is not my design. It was created by Kyle Emerick and is available on his website sandyeggo.com .
It is about 18" in diameter and carved on 3/4" MDF. I used a 1/4" tapered ball nose for the relief carving and a 60° 1/2" V bit for the finishing pass. I sealed the whole thing in a 1lb cut of dewaxed shellac, then sprayed it all silver. When the silver had dried for a few days, I smeared in the water-based black acrylic then cleaned the black off the surface, first with water, then with mineral spirits.
I got back on the longmill yesterday and tried the Star Wars version with some MDF. Yikes, it came out looking like some old shag carpet. If you squint and side-eyed it you kind of see the detail. It was the first time I did anything in MDF that wasn’t a profile tool path.
@Swinly Much depends on the bits and feeds and speeds you are using, Lonnie.
What size is your calendar? What bit(s) did you use and what were your feeds and speeds? How deep did you cut?
There is no magic to working with MDF. Generally, it is much more forgiving than solid wood, as there is no grain direction or density to take into account. (That said, there is some really, really bad MDF out there in big box stores.)
Get back to me and I’m sure we can get you some better results.
When I get back in the shop later I’ll make a note of the info and post it. Likely later in the day though.
My workflow was a little chaotic when getting back on it. I got a huge order for some of my power-carved crosses leading up to Christmas. I love making them but they take a lot out of me. Looking forward to more learning on the Longmill.
I like the finish you’ve applied. Any reason you didn’t stick with waterbased products throughout? I know from experience that their drying times are considerably faster than solvent based ones.
Marty from Kingston, ON, Canada
To your question. I tend to use whatever I have on hand. Most of my projects are binned after I’ve done them, so keeping the cost of my hobby down is important. In this case, I had the dewaxed shellac and the silver spray bomb. The shellac works well to seal the carve. I use it frequently. My wife had the silver kicking around from a last-year’s Christmas project and I “borrowd” it. Likewise with the black water-borne acrylic.
I don’t worry too much about drying time. I’m not in a production environment and tend to let things dry over night regardless.
Thank you for offering some help and sorry it took me all day and evening to get back to you.
The calendar I was attempting is 15in
I think I set a limit on the max depth at 0.35in- I messed around with tool paths in carveco and saved it when I shouldn’t have. If I didn’t set a limit then it would be 0.47942in
V cut tool path
Roughing I used 0.125in flat endmill (think it may have been an up-cut)-
stepover 0.05in
stepdown 0.2in
feed rate 80ipm
plunge 40ipm
RPM in carveco it is set at 15000 but I had it around 12000 on the router
V bit carve was a 60* 0.5in Vbit
stepover 0.075in
stepdown 0.25in
feed rate 40ipm - I bumbed the speed 30% as it was running
plunge 20ipm
RPM 18000- but on the router, I had it at about 14000
First, the calendar files that SandyEggo offers are based on a 24" diameter calendar. I only know that because he told me so. So, when we reduce them, we also complicate matters wrt possible level of detail. Mine was 18". The Dell Comics one that I did was 15 or 16 as I recall. What this means is that we need to use smaller bits and shallower cuts to get anything near a good result. OK, lecture over.
WRT to your specific specs:
I used a tapered ball nose with a tip of about .03", along with the V bit. You can use the .125", but it will not cut much as there are not many parts of that job that are big enough for that bit. (The biggest area is in the centre around the JB character and it will do a good job of that.) Use a down cut if you have it. The upcut will leave fuzzies on the surface.
Your max cut depth should be no more than .125" on a calendar that size.
I ran the tapered ball nose first, with a max depth of .125, then the 60° V bit with the same max depth. If you stay with the .125" bit, run it first, then the V bit.
Home Depot MDF is not terrible. It’s simply not the best quality out there. You can get good results with it though.
Finally, if you don’t mind the time it takes, run the V bit tool path twice, with no changes at all between the first and second run. For really clean cuts, coat the material with a 1lb cut of de-waxed shellac between the passes. (This is overkill, but it will make an observable improvement.)
I did another one and enlarged it with a max depth of 0.125". I used the down-cut bit this time. I didn’t have any shellac so I used a really fast drying sanding sealer. One and a half finishing runs though. It was diffidently making an improvement over one run. My laptop USB connection is starting to get a little loose and disconnected so I scraped the second run.
