Help me understand the difference in bits?

[myxpykalix]

I am interested in doing some sign work, lithopanes and other type of work and when i ask about the type of bits to use I get responses but that leads to other questions and confusion. I know in sign carving you use V carving bits but there are many different ones and how can i know what bit to use on a particular project? For example when i went to woodline.com here is what i see:
60° Three Flute V Groove & Carving Bit, 5/8" Diameter, 1/2" Cutting Length, 1/4" Shank
Our Price: $18.00
60° V Groove Bit, 1/2" Diameter, 5/8" Cutting Length, 1/4" Shank Our Price: $10.00

60° V Groove Bit, 3/4" Diameter, 13/16" Cutting Length, 1/4" Shank Our Price: $12.00

90° V Groove Bit, 1/2" Diameter, 1/2" Cutting Length, 1/4" Shank Our Price: $8.00

90° V Groove Bit, 1/4" Diameter, 5/16" Cutting Length, 1/4" Shank Our Price: $7.00

90° V Groove Bit, 3/4" Diameter, 5/8" Cutting Length, 1/2" Shank Our Price: $12.00

90° V Groove Bit, 3/8" Diameter, 1/2" Cutting Length, 1/4" Shank Our Price: $7.00

90° V Groove Bit, 5/8" Diameter, 1/2" Cutting Length, 1/2" Shank Our Price: $10.00

90° V Groove Bit, 1 1/2" Diameter, 1 1/8" Cutting Length, 1/2" Shank Our Price: $24.00

90° V Groove Bit, 1 1/4" Diameter, 1 1/8" Cutting Length, 1/2" Shank Our Price: $18.00

90° V Groove Bit, 1" Diameter, 3/4" Cutting Length, 1/2" Shank

What confuses me is the different diameters and cutting lengths how can I know what to buy, much less, what specific one to use on a project? Does anyone have a sign file, or anything, as a sample that has instructions as to what bit to use, that they could send me? I know you can't use a 1/2" upcut spiral to cut a lithopane (duh!) but I wouldn't know whether to use a 60 degree or 90 degree or 3/8" or 3/4" diameter bit to V carve a sign. Hope i explain it sufficiently to understand . Thanks

[ryan_slaback]

Jack, the main thing to remember when V carving is that the steeper the angle of the bit (60 degrees) the deeper it will carve the letters. If it is a 90 it would be shallower. The widths will be the same. If you go into the tool database in partwizard there is a good diagram that shows you what each of the dimensions are.

[scottcox]

Jack, something to also remember is the diameter of the bit. If you have a small diameter bit and a wide v-groove, you'll have to do multiple passes. A wider bit will do a wide groove (or letter, etc.) in one pass.

[rick_woodward]

Jack. I assume you will be cutting signs in 3/4 " and 2 by stock. For starters i would get the 60deg x 3/4dia. 90deg x 1/2" dia.
90 deg. x 3/4 dia. 90 deg.x1 1/2" dia. And get a 120 degree v bit x 1 1/2" The 120 deg. will let you do letters that are big in 3/4" stock or thicker.
I have the original 3 flute 60 degree x 1 1/4" x 1/2" shank from my starter kit from shopbot. I can do most things i need with those. The size and width of your letters will give you a visual cue with some trial runs. I dont know about if insignia or part wizardwill tell you,but Artcam pro will tell
me if a bit will be too deep. In 3/4" stock, your letters bigger than , say 1 1/2" tall would probably require a 90 Degree bit. And it will look better. Smaller letters use a 60 degree. The smaller diameter bits in any profile, 60 deg. or 90 deg. will allow you to get the lettering done in more confined areas. The ones i mentioned will get you going and do alot for you. Those are good prices on the bits. I have bought from pricecutter.Hope this helps. rick

[jhicks]

Jack, I would recommend the following.
1) Check out insert cutter bits from Hersaf or similar manufacturers. yes the base holder and arbor cost more but you can replace with sharp cutters quickly and cost effectively.Sharp cuts require sharp bits!
2)The starting point should include primary capability with a 60, 90, 120, and 140 degree angle v bits or as many as you feel you can afford or require for your projects.
3) When/if the font is wider than your bit diameter or deeper than your max cut depth/pass it will pass over the area multiple passes until it achieves the width/depth based on width to depth ratio for that angle.Unless you have a max cut depth set, it will go as deep as it needs to to achieve that width. ie: a 1" diameter 90 degree v bit will go .5" deep for a 1.0 " wide letter area by taking multiple passes based on what you set as max cut depth, step over, etc for that bit. But if you ask it to cut a 2" wide letter it will need to go 1" deep and your bit library will dictate if this is possible and what the cut depth per pass, step overs etc will be.
4) To verify the depth of cut either calculate width to depth ratio on your bit or depending on your software, generate a tool path/ simulation and check the cut file. You can scroll down the tool path or view in preview simulation searching for the various or min/max Z depth on the font areas and discover if you are going too deep or shallow for your goal and material.
5) Once you determine the depth you desire, you can decide if some fonts should be cut with a 60 or 90 and others wider/narrower. You may want wider fonts, borders, or artwork to be cut with a 120 or 140 degree for example to achieve simular depths to the 90 in narrower or smaller fonts for a specific or more consistent transition between different width letters/artwork.

[paul_z]

Jack,

There can be an issue with the accuracy of the angle of the bit. Some bits are a couple of degrees off the advertised angle. Suggest that you check the actual angle before using the bit. Some (most??) of the programs will allow you to define a new bit of the actual angle if the bit is not as advertised.

Paul Z

[knight_toolworks]

one simple thing is the diamiter is not critical as long as it is big enough for the job. since the angle is the same the larger the diamiter the deeper you can go. but you can also do small thigns with the larger size. so get the largest size you will need and it will do the smallest things you want to do.