Help me finish this...

[dmidkiff]

Steve,

I have a 1/4 X 1/8 bushing and it has worked fine when it was used. Don't use it much and would look for something different if I used it alot, because of getting it chucked up just right. I use a PC router and found a 3/8" collet. I think I found it at precise bits where I got the bushing.

Good job, very informative.

[steve_g]

Basic Router Bits Ver. 3.0

Lots of changes, getting close I think... I'd add more "practical tips" if someone has something to say... I think I have all the bit rotations straightened out, and the Ball end /nose issues fixed. I put a greater emphasis on chip load (now three pages worth).

Tell me what you think of:

• the use of color (trying to not be boring)
• Caution items in bold red (no icons)
• The amount of info on a page. (too much?)
• Have I gotten away from the mission? (basic router bits)
• total length... will people seeking answers read the whole thing?
• any thing else I've missed

Steve

Again... the graphics display better if the PDF is downloaded rather than viewed over the web.

https://docs.google.com/open?id=0B8GtiBWUjRyRSi1RWXNIWTRRbXFfQU9NanlxMDR2Z w

[dana_swift]

This is an excellent document!

Steve- do you mind if I give out copies? I sometimes teach people how to run the shopbot at FabLabTulsa. Your work is exactly what is needed.

Its not too basic for someone staring out. If they happen to be familiar with part of the subject material they can skip that part.

Its not too long, and not too detailed.

About the only other things I might include is references to such things as the machinery's handbook, and sites with chipload/rpm formulas and tables like:

For metals:
http://its.fvtc.edu/MachShop3/SpeedC...edratecalc.htm

For non-metals:
http://www.cutter-shop.com/main.asp?...eds_and_speeds

The tables provided on these sites are the best reference I have found so far for chip load starting points.

One other point you dont mention is depth of cut. That depends on the actual torque available to the bit at the cutting RPM. Seperating any given hardness of material requires a certain sheering force per inch of cut. The torque in the shank of the bit becomes the available sheering force at the radius. Most of us learn from listening to how hard the machine is working as to whether we can cut deeper or shallower on a material and adjust future cuts based on the experience. The worst case is a stalled bit.. followed by "bits of bit".

Steve: You have produced an excellent document without any of the above! At some point you will have to decide its "good enough" and call it done for now.

Thanks for all your efforts..

D

[chiloquinruss]

Great piece, thank you for sticking with the project to get it complete. Russ

[dlcw]

Steve,

I just read the document completely. You did a GREAT job on this! I wish there had been something like this when I first started playing with the CNC. I was always scared to push the machine because I didn't want to 'break' bits. But as you note, it turns out that going slow was the cause of overheating and 'breaking' bits. Live and learn (expensively).

I think this should be REQUIRED reading pushed by Shopbot for anyone who purchases a CNC from them. It would eliminate a lot of tech support calls for Gary though .

If I hire anyone (economy turn around) this will be required reading.

[steve_g]

Thanks all for the kind comments... Dana and any one else interested, I don't consider this "my" document... I'm the editor at best. It is my sincere hope that you will copy and use it in any way appropriate. I do however feel it's only right to retain the ShopBot and Forum references intact.

Hopefully this will be a dynamic or "living" document and be updated as necessary. I will add the links Dana supplied in 3.1, and continue to solicit photos and stories from members experiences.

Again... the PDF was produced from a power point file. The PP is available to all who can use it in that way.

One note of concern... Along with the photos and drawings I generated, I also shamelessly appropriated Images from the web. If this article will be used out side of the forum, do others feel it will be necessary to recreate our own images100%?

Steve

[beacon14]

"The speed at which a Router spins the bit is called its RPM (revolutions per minuet)."

How many times can one spin a router bit during the typical minuet?

Also, in the discussion of cut direction, I believe you have your descriptions reversed. A clockwise cut around the perimeter of an outline would produce a climb cut, while counter-clockwise would be a conventional cut. Good job on fixing the rotation diagram.

"The solution to this dilemma is to cut to each methods strength. Climb cut an object allowing .01” - .015” then make a final pass, full depth without allowance in a conventional direction. This method, called an Onion Skin strategy, will often result in the best possible finish on a part."

This makes perfect sense to me as I already understand the concept, but I could see how this would be ambiguous to a beginner. Is the allowance left on the size of the part, the depth, or both? I could see this benefiting from some clarification. (What is an 'allowance' anyway? I used to get $.50 every Sunday as my allowance.) Onion Skin refers to not cutting full depth on the 1st pass (to maintain full vacuum until all the rough cutting is complete), while allowance refers to leaving the part oversize on the 1st (typically climb-cut) pass. Either method could be used with either conventional or climb-cutting. It's the right combination of all three of these concepts that produces the best combination of part size, edge quality, bit life and hold-down success.

Overall this is an excellent document, and I plan to share it with my employees, students, and anyone else who will be running my machine. Thank you for putting in the significant effort to produce this manual. One last impression, the opening paragraph kind of gave me the feeling I was being pitched something by a snake-oil salesman, I was almost wondering if this was an introduction to something that was tailored to get me to buy something, especially when the last sentence refers to products available to buy. Not a big deal, but you did ask for feedback. I think the use of color is just right, enough to be interesting without being distracting. As for the images, unless they were copyrighted I don't think using them would be a problem, content is "appropriated" from the web and re-printed every day. Others may disagree.

Thanks again.

[steve_g]

David
Your feed back is EXACTLY the kind I was asking for... Thank you!

"The speed at which a Router spins the bit is called its RPM (revolutions per minuet)."

would "Rotate" be better?

I believe you have your descriptions reversed

Is that the perspective of the router or the product? ... really I think you're right, I changed the drawing and didn't re think the CW CCW terms.

This makes perfect sense to me as I already understand the concept

I'll clarify this as I did say "no previous knowledge assumed". My understanding was that Onion skin referred to both perimeter and depth... I will defer to your explanation as it makes perfect sense.

the opening paragraph kind of gave me the feeling I was being pitched something

Yes, me too. I was trying to be humorous. interesting and pique ones interest. I admit it fell short... Anyone else care to have a stab at an introduction?

Steve

[rcnewcomb]

I was confused by the statement, "More flutes increases the strength of the tool". Do you have a source for this information? It would seem to me that more flutes would weaken the tool.

[steve_g]

Randall,

I know... it sounded counter intuitive to me too at first. I didn't find my original source right off but it had a drawing similar to the first one I've attached. I also attached a real life photo of 2 VS. 3 flute. The 3 flute is obviously "beefier" due to shallower gullets and hence the reduced chip flow area.

What I haven't figured out, and was hoping some one would question, is multiple sources say you can cut faster with a single flute free flowing chip design than a 3 flute bit. However if you enter the data into chip load calculator it says to cut faster with the 3 flute design. Any one have some insight here?

Steve