Router bit sharpening question?

[drodda]

Anyone on here know someone who does router bit sharpening? I have over 200 hundred 1/4" downspiral whiteside bits that need sharpening. I checked with a local guy and he wanted more than I am paying for new bits.

Any help is appreciated.

Dave

[gerald_martin]

Hello Dave: Check with Great Lakes Custom Tool. Their website is http://www.glct.com/

I have bought Onsrud and Whiteside cutters through this company and have had them resharpen cutters as well. My experience was that the bits cut as good as new if not better. I think it was about $5 per bit.

Not an endorsement, just what worked for me.

Gerald Martin

[drodda]

Gerald,

Thanks for the link, one question though, are the bits still .25 inch in daimeter once they are sharpened or do they lose a litle size?

Thanks,

Dave

[nschlee]

In the past when I have had my .25" downspiral 2 flutes bits resharpened the majority come back at .220" with the balance .235". Usually I can run the .235's as .250's but make new files for the .220's when running production files. Vortex is who I've used in the past, $6 ea. 100 min. a few years ago, may be more now, excellent quality.

Neal

[don]

Dave,
I used to sharpen tooling for approx 15 years.
To resharpen endmills they need to grind the diameter.
Usually they need to grind off (approx .005 - .010" which is only .0025 - .005" a side), depending on how bad the edge is.
Each time you grind the diameter, the Hook and Rake (Geometry inside the flute) changes.
After grinding approx 15% of the diameter of the tool, your tool won't the edge or isn't as sharp after a few regrinds. ( this is because of losing the hook and rake geometry).
The Higher end shops can regrind the Hook and Rake and bring the tool back into spec.

You can get things reground any where from $4 - $10.
And just like Botters, they can do just a piece or two, but would rather have several. 10 - 15 pieces is a nice run for them to set up on.

Some FYI....
Just to regrind the diameter there's at least 7 different parameters they use for grinding the diameter.

Primary angle
Primary width
Secondary angle
Helix
Flute Length
Diameter

[myxpykalix]

Don,
Let me ask since you seem to have the experience, if you regrind the bits and take off the amount you describe wouldn't you have to adjust your tool parameters within the tool description dialog boxes to get an accurate cut since you now have a .23" tool instead of a .25" tool or am i overemphisizing it? At $10.00 to regrind a $20.00 tool seems foolish but $10.00 to regrind a $150.00 is reasonable.

[drodda]

Jack,

My thoughts are pretty much the same. Is the smaller diameter worth the price difference? The end mills cost $12.50 new and I am not sure that even for $5.00 it is worth the hastle. I am just getting tired of looking at my box of used 1/4" downspirals and was trying to figure out what to do with them. If I could find someone to sharpen them in a barter situation it might be worth it for non precise cutting. Something like send in 250 bits and get 125 back sharpened they get to keep the other half for their labor.

Thanks for the replies though. It kind of confirmed what I was thinking about these bits.

Dave

[don]

Jack you are correct.
If you have files that are already setup for the .250" and they came back .240"/.230" diameter, you would have to recalculate your tool path with the new diameter.
But if you were to take in 20-30 of your dull .250", I'd ask them to grind them all to the same diamter.
So you only have to recalculate your file just the one time, along with changing your tool database.
You should do this every time you get a new tool because the rule of thumb is plus or minus .005 is with in tolerance.

Dave, I understand what your saying. It can be a hassle sometimes.
But if you have a local cnc grinder, They may even come pick them up and deliever.
You might even ask if they have a market for your scrap carbide tools.

If it was me I'd regrind them.
If they know what their doing then can get several regrinds out of a tool,
especially if they reflute and correct the hook and rake angles.

I never throw away anything that has a 1/2" shank or larger,
I may need a custom shape or end made.
Its cheaper to rebuild than to buy new.

I no longer grind tools for a living.
But I'm in the middle of putting a toolgrinder together to sharpen my own.
I may take you up on that offer Dave.

[curtiss]

When do you know the bits are beginning to get dull, say in mdf ?

Do you try to run them a given number of hours ?

Do they simply begin to run hot ??

[drodda]

I only use the bits for a single project. I have a system that I use and I price the bits into my costs for the table projects so I use them and then put them in the box. I know there are tools in there that are like new and others that are used and abused. It just is no cost effective for me with time and materials to use a bit till it is so dull it tears up the workpiece. Very clean cut quality is more important than getting all the life out of a single bit.

Dave

[angelosart]

is it possible to resharpen 1/8" or 1/16" ball nose bits?

[donek]

In my experience, most sharpeners just shorted the bit. You typically only cut with the bottom on the bit anyway, so you cut/grind the used portion off and grind the bottom to the correct shape.

I cut a fair bit of aluminum with my Router and always purchase the longer O-flute bits. They can be easily ground on my bench grinder. The typical depth of cut with these bits is 0.050in. Anytime I've lost the cutting edge it has been the very tip. I just grind off a bit and then regrind to the shape of the new one I have in my bin. Depending on the material I'm cutting, I'll usually grind multiple times before the stub of a flute that's left is too short for the 1/4 or 4mm material I sometimes cut, saving the longer cutters for the 1/2 and 3/4 material.

If you've got a pile of dull cutters, I say try to do it yourself. What do you have to loose, other than something that's currently useless to you. Once you learn how to do it right, you turn a piece of garbage into a $30 cutter for 5 minutes of your time.

Reading glasses are your best friend.

[solidwoods]

Could a Shopbot be set up to grind bits?
4 or 5 axis may be needed, plus proper spindle speed and maybe coolant, but is it possible to configure as a tool sharpener?
I sharpen many tools that I use for my business because some sharpening in house make profit/convenience for my business model.
One could also factor the 4th 5th axis would make money other ways also v.s. a dedicated tool sharpener which if not cnc could be less flexible/multitask-able.
jim