Patternmaker's letters

[Dr Stan]

What is the height of the letters you want?  You may be able to find some at a office supply store that carries letters & numbers for display boards like the ones used to give office numbers of people and commonly located in the lobby of a office building.

[Pete O]

That's a thought Stan, I need them about 3/4" tall or a little less, which would be at the smaller end of anything I've seen in that line but definitely worth a look. We have a place in town that I'll try.

[Pete O]

I've made reasonable progress on carving out the pattern board. Got the alphabet done and the numerals and punctuation marks are ready to carve. The font is 72-point 'Franklin Gothic Book' in bold, it's just on 17mm tall.

   
I seem to have acquired a vertical spindle-moulder that came in quite handy for bulking out around the letters
   

and I appear to have tomorrow's work cut out for me
   

This is about the most arty-crafty thing I have done since I left school over forty years ago. Coming along ok I think, I'm tossing up whether to cast the negatives in the hyper-expensive soft rubbery stuff that I have left over from a previous project, or plaster of paris. Might be decided by how much of the rubber stuff I have left. The final positives I think will be fibre-reinforced auto body filler.

[arvidj]

(06-04-2019, 08:49 PM)Pete O Wrote: ... I'm reluctant to ask anyone else to put time into it on my behalf.

Pete,

What you are currently doing looks great but if it does go pear shaped (I'm sure it will not) then let me know.

Just wanted to give you some idea of what the 3D printing process is ... at least in my case.

As far as the time ... you will spend a lot of it looking for the correct font and determining size. I then spend a small amount of time (an hour at the most) taking the .stl files associated with the font you have selected and running it thru a slicer to get the gcode file. I would then get the gcode over to the printer and start the printer ...  minutes max.

The printer then clicks, beeps, and makes stepper motor sounds for multiple hours. Note that this is a totally unattended process and I get other things done while that happens so my time would be zero for that phase.

Then pack it up and send it to you ... another hour max.

TL;DR; You will spend more time picking out the font than I would printing it.

I spend much more time with my CAD software coming up with the model and getting to a .stl file than I spend actually printing the .stl file. The actual printing takes a lot of clock time ... multiple hours ... but for me that is usually a 'set it and forget it' deal.

Arvid

[Pete O]

Thanks for that Arvid, it's something I have absolutely zero knowledge about. I came close to bidding on a printer at the same die-maker's clearing sale where I bought my surface grinder, but backed out as I had a suspicion I would be uncovering a rabbit hole nearly as deep as the one I found when I first got a lathe.
I'll continue plodding along with my polynesian-style woodcarving for the present. I've just started a couple of months long-service leave with no real plans other than to potter around at home and spend some time with my wife, so I have no problem spending a couple of days on this. If it doesn't yield a result, I'll tap you on the shoulder to unpack a little more for me of how to obtain files etc. I really appreciate it.

[rleete]

Cheap desktop 3D printers can be had for less than 100 bucks, shipped. That's a complete, take it out of the box and start printing one, not a kit. Search monoprice.

If you want used, they go for $50 and up.

[arvidj]

(06-05-2019, 07:38 AM)Pete O Wrote: ... I had a suspicion I would be uncovering a rabbit hole nearly as deep as the one I found when I first got a lathe ...

There are many of us that are proof the suspicion is all together too valid.

I'll post something on another thread later this week that either confirms a 3D printer is something that is handy to have around or confirms that having one will cause you to spend too much time and energy creating an over-kill solution to what may have been a simple problem.

[Vinny]

I don't know what expensive rubbery stuff you're referring to, but Smooth-On has a number of rubber mold making materials that aren't that expensive. I would suggest Dragon Skin 10NV. Very rubbery, easy to get your model out of and will go right back into shape. Trial size, last I looked, is about $25-$30 US for what they call a pint. It's actually a pint of the rubbery stuff and a pint of the hardner that you mix 1:1 so in reality you get a quart. That's enough to make 2-3, maybe more, molds of your letters. The mold doesn't have to be more than an inch deep based on what your letters look like. The 10NV is thin enough to mix easily, has a fairly short cure time and is thin enough to not need vacuuming to remove the air. You have 15 mins to mix and pour, then it takes 75 mins to cure.

[Pete O]

That sounds very much like the stuff I have Vinny, although as so often happens the products here are from different manufacturers or go by different names. I bought this stuff a couple of years ago to make soft motor mounts for my phase converter to help quiet it.
   
   
It's got a slightly longer cure time than what you mention but the motor mounts have just the sort of consistency that should work well for a mold, flexible enough to pop the parts out once they're cured. I have a pressure can of release agent to go with it. The seller used to be just near where I work but he's moved to a different area, so to get stuff like this is a half-day outing for me. I was glad to find there was enough left for this job. I think I spent close to a hundred bucks for this stuff, the release agent and another small quantity of 2-pack primer that makes the rubber compound adhere to the metal for applications like those motor mounts.

I got my carving finished this afternoon, sprayed it with paint to seal the surface.
   
So this board of positives is step 1, pouring the rubber over the board to make a set of negatives will be step 2, casting the letter patterns in the soft mold to make the individual positive blanks will be step 3, attaching them to the pattern and ramming the casting sand for a complete negative cavity will be step 4, and pouring the metal for the finished part will be step 5. Plenty of opportunity for things to go wrong along the way. I expect the letters produced at step 3 will need some fettling before attaching to the pattern, it should be easier to tidy up things like internal features- the holes in letters like O, P, B etc- when I can hold them in my hand and pass a needle file through them.

[f350ca]

Nice carving Pete