Sharpen a dull holesaw (YES it works!)

[Sodo]

Yes it can be done, easily done.
(Probably just once though.)

Holesaw was visibly dull and I wondered if it was gonna cut at all?
Well, It did ..... about halfway, smoking the oil, and hardly any chips (only dust) coming out.

Some of you have Been There Done That?

So using a narrow kerf cutoff wheel in the angle grinder I gave a little love-tap to the backside of each tooth.

This pic you can see the 3 rightmost teeth are untouched, you can see the flat spots ( DULL ! ).
And you see grinding on the sharpened teeth on the left teeth.
I inspected each tooth again after this pic, giving the teeth that didn't have a cutting edge another love tap.
Note that saw teeth are bent (alternately) inward and outward (called "the set).
You don't want to grind too far down (to lose the set) or there's no room for the saw to eject chips.
Or to pry out the round plug when you're done.
With that in mind, I kinda doubt you can sharpen a holesaw more than once.

This is a 1-3/4 holesaw, theres not that many teeth.

It took less than 5 minutes to do this and then it cut very well.
Maybe not as good as a new saw - but pretty good dang-it -
Its good enough to put this old cutter back in the drawer (rather than throw it away just yet).

This could be a problem, as in the past I'd discard them,
-and remember to buy a new one of that size.
but now Im inclined to keep them even if dull, and then forget what size I need to replenish.

Ya know - when you NEED that size.... and its 5 minutes to sharpen...
Or 30 minutes roundtrip to the store.

....or my case today, out here in the woods, 90 minutes roundtrip....

 

[MossRoad]

Neat! :thumbsup:

 

[fried1765]

Yes it can be done, easily done.
(Probably just once though.)

Holesaw was dull and I wondered if it was gonna cut at all?
It did ..... about halfway and hardly any chips (dust) coming out.
Some of you have been there done that?

So using a narrow kerf cutoff wheel in the angle grinder I gave a little love-tap to the backside of each tooth.
I suppose some of you BTDT too.
But heres a pic.

This pic you can see the last 3 rightmost teeth untouched, Note the flat spots (dull).
And the sharpened teeth on the left.
I went around again after this pic, giving the teeth that didnt have a cutting edge another love tap.
This is a 1-3/4 holesaw, theres not that many teeth.

It took less than 5 minutes to do this and it cut well. Not as good as a new saw - but dang-it - its good enough to put the old cutter back in the drawer (rather than throw it away).

This could be a problem, as in the past Id discard them, -and remember to buy a new one of that size.
but now Im inclined to keep them even if dull.

This can be a problem.... but Ya know - when you NEED that size.... and its 5 minutes to sharp...
Or 30 minutes roundtrip to the store
or my case today, out here in the woods, 90 minutes roundtrip....

GOOD INFO!
Thanks!

 

[grsthegreat]

never tried that...may give it a go. i have maybe 20 dull holesaws. i use them when installing transfer switches. I recently tried the new Milwaukee Carbide hole saws. those are great little units. costly but they really last. Ive had lennox holesaws dull after 1 job. The carbide unit has done 5 and is still sharp.

 

[radios1]

using a dremel is a lot safer, and notice the teeth reverse direction of grind angle each tooth.. that prevents binding.

 

[Sodo]

RADIOS1 I didn't grind on the cutting edge, I just took material off the backside of the tooth to get a 'point'.

Agreed a Dremel and magnifying glasses could get more re-sharpens out of a holesaw.
And re-sharpening it BEFORE the teeth are flat ontop.

But in this case I had the proper size but DULL,
and wanted the hole done NOW,
No time for a "proper" saw sharpening (as often the case)
...and intended to get a new holesaw for next time (that too).
Which I was successful with regards to my goal....... but probably won't be (in remembering to replace it)

GRS I've used Lenox holesaws many many times, continually amazed how long they *can* last.
I think of every holesaw as almost a "one-use tool" but not Lennox, which I think might last 5 holes, then pleasantly surprised often when one lasts 20, 30, 40 holes in 1/4" steel etc.

It comes down to speed and lubrication.
For every diameter, there is a speed that results in a tooth speed that's "too fast" and the holesaw won't last.
If you can drill at the proper speed (and with cutting oil) they last a long time.

Drilling straight down can cost holesaw lifetime too because the chips can't fall out.
You tend to WANT to drill vertical, because it's easier, as in a drill-press.
But then you need to spin it too fast to eject the chips back up out of their groove.
It's good for the operator, but wrong for the holesaw.

If you can, the cut should be angled so the chips can fall out.
Slower speed (for bigger diameters), with oil and they stay sharp a LONG time.

Somewhere there MUST be a holesaw speed chart (now just need a tachometer on your drill....)

 

[grsthegreat]

RADIOS1 I didn't grind on the cutting edge, I just took material off the backside of the tooth to get a 'point'.

Agreed a Dremel and magnifying glasses could get more re-sharpens out of a holesaw.
And re-sharpening it BEFORE the teeth are flat ontop.

But in this case I had the proper size but DULL,
and wanted the hole done NOW,
No time for a "proper" saw sharpening (as often the case)
...and intended to get a new holesaw for next time (that too).
Which I was successful with regards to my goal....... but probably won't be (in remembering to replace it)

GRS I've used Lenox holesaws many many times, continually amazed how long they *can* last.
I think of every holesaw as almost a "one-use tool" but not Lennox, which I think might last 5 holes, then pleasantly surprised often when one lasts 20, 30, 40 holes in 1/4" steel etc.

It comes down to speed and lubrication.
For every diameter, there is a speed that results in a tooth speed that's "too fast" and the holesaw won't last.
If you can drill at the proper speed (and with cutting oil) they last a long time.

Drilling straight down can cost holesaw lifetime too because the chips can't fall out.
You tend to WANT to drill vertical, because it's easier, as in a drill-press.
But then you need to spin it too fast to eject the chips back up out of their groove.
It's good for the operator, but wrong for the holesaw.

If you can, the cut should be angled so the chips can fall out.
Slower speed (for bigger diameters), with oil and they stay sharp a LONG time.

Somewhere there MUST be a holesaw speed chart (now just need a tachometer on your drill....)

when cutting a 2-1/2" hole horizontally to install a transfer switch, i cannot use lube or drill vertically. My holesaws were drilled at slow speed, but sometimes never made it thru one hole without dulling. the carbide bits dont seem to have that issue.

 

[4570Man]

RADIOS1 I didn't grind on the cutting edge, I just took material off the backside of the tooth to get a 'point'.

Agreed a Dremel and magnifying glasses could get more re-sharpens out of a holesaw.
And re-sharpening it BEFORE the teeth are flat ontop.

But in this case I had the proper size but DULL,
and wanted the hole done NOW,
No time for a "proper" saw sharpening (as often the case)
...and intended to get a new holesaw for next time (that too).
Which I was successful with regards to my goal....... but probably won't be (in remembering to replace it)

GRS I've used Lenox holesaws many many times, continually amazed how long they *can* last.
I think of every holesaw as almost a "one-use tool" but not Lennox, which I think might last 5 holes, then pleasantly surprised often when one lasts 20, 30, 40 holes in 1/4" steel etc.

It comes down to speed and lubrication.
For every diameter, there is a speed that results in a tooth speed that's "too fast" and the holesaw won't last.
If you can drill at the proper speed (and with cutting oil) they last a long time.

Drilling straight down can cost holesaw lifetime too because the chips can't fall out.
You tend to WANT to drill vertical, because it's easier, as in a drill-press.
But then you need to spin it too fast to eject the chips back up out of their groove.
It's good for the operator, but wrong for the holesaw.

If you can, the cut should be angled so the chips can fall out.
Slower speed (for bigger diameters), with oil and they stay sharp a LONG time.

Somewhere there MUST be a holesaw speed chart (now just need a tachometer on your drill....)

I think throwing away the drills geared too high to run slow and using a high toque low speed drill is the single best thing that could be done for keeping a hole saw sharp.

 

[Billrog]

I agree with 4570Man and I also have sharpened a no of hole saws with a dremel tool but on the cutting face .

 

[Oldoak]

I used a countless number and sizes of holesaws during my career. Speed and feed as well as cutting lubricant is the key to holesaw longevity. Too much pressure will cause the holesaw to dig in and either stall the drill or break off teeth from the holesaw. Too little pressure will round off the tips of the saws teeth.

Granted, a hand held drill is difficult to maintain a constant rate of feed like when using a drill press or magnetic base drill.

There are also cutting lubricants in the form of a wax like stick used when cutting holes in the overhead and horizontal positions or in an environment where liquid cutting oils are not acceptable.