Minimum Font Height

Bill Arnold

1974
Staff member
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Thomasville, GA
From a practical standpoint, what is the minimum font height to plan for when cutting a plaque?

The reason for my question is that I've done a couple of tests for a plaque I want to make. I used a 60° v-bit in mdf. It looks OK but I'm trying to envision how well it might cut using vinyl masking over hardwood.
 
I think the short answer is: That depends!

Let's assume you have a super perfectly sharp point on your v-bit - in theory, your smallest size will mostly depend on how well your material holds up (do the insides of P or O or A stay together?) -- so it still depends ...

In MDF, with a 60 degree cutter, assuming it has a really good sharp point (not all of 'em do!) and can cut a fine line, then you could get pretty small ... 1/4" tall letters aren't out of the question. You may be able to push it smaller with some kind of pre-treatment to harden up the surface of the material (like wood hardener, CA or even a few coats of finish like poly or shellac soaked in).

To a lesser extent, your machine may influence this, too - if you have a little backlash, it can become more apparent when trying to make a line of small text because some slight variations might make the baseline a little wiggly.
 
I think the short answer is: That depends! ...

Exactly what I expected. Interesting that you mentioned 1/4" tall letters because that's what I've got so far. One part of the item I'm laying out will have to be etched because it's a line drawing that looks like garbage when done with a V-bit. I'm thinking that my next test will be to do the text with an etching bit but go deeper than on the line drawing. As you can tell, I'm still experimenting! :huh:
 
As you can tell, I'm still experimenting! :huh:



That's how we learn! I'm interested to see what you discover. I've been contemplating some letters in aluminum, but I'd like to go smaller than 1/4" - maybe 3/16 or so. The V-bit i tried the last time did okay, but the part wasn't sitting very flat, so that had a lot of influence on how well the letters came out. I need a better fixturing solution or one of those spring loaded engraving type bits, I think.
 
... I need a better fixturing solution or one of those spring loaded engraving type bits, I think.

Yep, same here. My gantry is "level", base is "level", workpiece is "level". There are still very small variations and 0.5mm makes a big difference in an engraving and some v-bit work. I think my solution will be placing a new mdf base board and using a spoilboard surfacing bit to flatten it. I should be able to get a piece of wood flat before placing it on the machine! :dunno:
 
Yep, same here. My gantry is "level", base is "level", workpiece is "level". There are still very small variations and 0.5mm makes a big difference in an engraving and some v-bit work. I think my solution will be placing a new mdf base board and using a spoilboard surfacing bit to flatten it. I should be able to get a piece of wood flat before placing it on the machine! :dunno:



I've had a very similar struggle. Lately, the task has been to do the inlay for the headstock plate of my guitar build. It's 1/8" thick ebony, which isn't too bad since it just gets v-carved - as long as I can hold it flat, that does okay. The tricky part is doing the reverse on the inlay material - picture a male version of a v-carving (called v-inlay) - basically it's cutting with the same bit, a part that fits perfectly into a v-carved "pocket" to fill it perfectly with sharp corners and all that. CHALLENGING because the material I'm cutting that out of is 1/16" thick pearloid - floppy, and double stick tape just don't get it done (especially considering you have to peel this super thin onion-skin off the tape without ripping it apart).

This had me experimenting with a vacuum clamp of some kind so that I could hold that super thin stuff and cut ALMOST through it without destroying it. Very light cuts, lots of trials. Most surprisingly, it's working! I will be taking a look at the "for real" inlay tonight when i get home -- it went into the clamps last night and so I will get a look at whether I was successful or not. Sure hope so - that ebony is nice! :D
 
I have the equipment and materials to try vacuum clamping on my cnc but haven't tried it yet. My concern is the gasket material being even a tiny bit inconsistent. I'll have a go at it sometime, though.

As to some of the stuff you're doing - I need a LOT more practice!!! ;)
 
I have the equipment and materials to try vacuum clamping on my cnc but haven't tried it yet. My concern is the gasket material being even a tiny bit inconsistent. I'll have a go at it sometime, though.

As to some of the stuff you're doing - I need a LOT more practice!!! ;)

LOL - that's how I got to this point ... practice, and listening to (and often going against) leo :p

So far, about the only stuff I've got that works semi-okay is 1/8" thick neoprene. It's closed cell, squishy, and pretty dang consistent thickness and uniform density. Problem is it's just barely grippy enough for my liking - with 25" of vacuum, i can't slide stuff around real easy, but i can pop it up without much trouble at all - no up-cut spirals with this stuff. There'll be at least one video on this subject coming soon :D
 
Yep, I've got all kinds of ideas about things to try on this doo-dad - inlay, etc. With planning, I can see cutting intarsia components. And, then, I have the LOML factor, like, "When are you going to finish the trim around the guest room closet?" :bang:
 
Yep, I've got all kinds of ideas about things to try on this doo-dad - inlay, etc. With planning, I can see cutting intarsia components. And, then, I have the LOML factor, like, "When are you going to finish the trim around the guest room closet?" :bang:


Ohhh Ohhh Ohhh - I just gotta show your wife what the possibilities are for trim ---- but you are gonna HATE me
 
Yep, same here. My gantry is "level", base is "level", workpiece is "level". There are still very small variations and 0.5mm makes a big difference in an engraving and some v-bit work. I think my solution will be placing a new mdf base board and using a spoilboard surfacing bit to flatten it. I should be able to get a piece of wood flat before placing it on the machine! :dunno:

Best practice is the use the machine to mill the face before doing the text.

That is really the best way to ensure the face is parallel to the machine axis motion, not necessarily to the table.

Having it flat on the table is fine, but not exact.

This is especially important with small or shallow text - or anything really.
 
Ohhh Ohhh Ohhh - I just gotta show your wife what the possibilities are for trim ---- but you are gonna HATE me

Hey! She doesn't need any help with ideas!!!


I have cut several lines of clear and concise text into a space 1" x 2" ...

I've done some small text (about 3/16") using an engraving bit and I can see how I could go a lot smaller. My concern has more to do with small cuts when using a v-bit and vinyl mask.


Best practice is the use the machine to mill the face before doing the text. That is really the best way to ensure the face is parallel to the machine axis motion, not necessarily to the table. Having it flat on the table is fine, but not exact. This is especially important with small or shallow text - or anything really.

I hadn't really thought about milling the face of the material itself, but that could be a good solution when engraving something.
 
Hey! She doesn't need any help with ideas!!!




I've done some small text (about 3/16") using an engraving bit and I can see how I could go a lot smaller. My concern has more to do with small cuts when using a v-bit and vinyl mask.




I hadn't really thought about milling the face of the material itself, but that could be a good solution when engraving something.

The bit will "FIT" between the lines of the text, so what it really depends on is how wide the lines are apart. If there is a flat tip on the engraving tool of - say .010 and the width of the text is .010 - you will get nothing. This is one reason I look for really pointy bits that have cutting flute all the way to the tip. Then - you need to consider the angle of the bit. A 120 Degree bit will not be able to get into the space between the lines. A 60 degree bit will fit in and cut deeper. Go to a 45 degree bit and you will go deeper still.

Then there is the mask - which has thickness. I generally set my "Z" zero about .010 or so lower than the top of the mask.

Hope this makes sense - if not I will draw some quick sketches.
 
The bit will "FIT" between the lines of the text, so what it really depends on is how wide the lines are apart. If there is a flat tip on the engraving tool of - say .010 and the width of the text is .010 - you will get nothing. This is one reason I look for really pointy bits that have cutting flute all the way to the tip. Then - you need to consider the angle of the bit. A 120 Degree bit will not be able to get into the space between the lines. A 60 degree bit will fit in and cut deeper. Go to a 45 degree bit and you will go deeper still.

Then there is the mask - which has thickness. I generally set my "Z" zero about .010 or so lower than the top of the mask.

Hope this makes sense - if not I will draw some quick sketches.

All of it makes plenty of sense, Leo. Thanks for your input!

I've done a combination of live cuts and simulations to get an idea of how some of this stuff works. For instance, one item I want to make will consist of text that I'll cut with a 60° v-bit and a line drawing that will be cut with an engraving bit.

The engraving bits I have are 1/8" solid carbide 30° with a sharp point. I get good results at 1/32" to 1/16" cutting depth.

Since I'll be dealing with a fairly small text along with a line drawing, I'll apply sealer to the wood, make the cuts, then fill the cuts with dry dye powder followed by a coat of sealer and top coat. I've done a small-scale test like this and it turned out OK.
 
LOL - that's how I got to this point ... (and often going against) leo

HeHeHeHeHeHeHe

You have NO idea how I read all the forums and watch as so many people try different things.

Sometimes I speak up - though I am getting more mellow lately - and my advice goes to the wayside. I am OK with that - but when it comes back around I have all I can to not repost with -- nyah nyah - told ya so :rofl:

In reality - I learn a lot also.

I even learn stuff from you Jason.
 
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