# should I convert these?



## Pontiac Freak (Mar 5, 2017)

I was able to purchase a nice set of holesaws from a retired machinist.  All all new from the appearance.  I chuck them up up in a R8 collet and if they bind they slip.  I have ruined 1 collet so far due to slippage.  (They were tight!) My question, should I convert them from R8 collet to a 3 sided drill shaft?  Pro, cons?


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## FOMOGO (Mar 5, 2017)

What speed are you running, what are you cutting, and are you lubricating/cooling? Mike


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## Pontiac Freak (Mar 5, 2017)

FOMOGO said:


> What speed are you running, what are you cutting, and are you lubricating/cooling? Mike


RPM - 60.  Lowest I can go on my mill.  Lube - Yes, tap and die cutting fluid.  Lots of it.  Cutting mild steel up to 1" thick.  Cutter wall thickness is .100.  These are beefy hole saws.  Havent come across any like this before.  They are capable of being resharpened.  But when they grab they slip.


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## kd4gij (Mar 5, 2017)

What Mike asked. And I would get an weldon  end mill holder and mill a flat on the shank.


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## Pontiac Freak (Mar 5, 2017)




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## FOMOGO (Mar 5, 2017)

The cutting edges seem inconsistent, If some teeth are protruding further than others it would be prone to grab. Try setting it on a flat surface and see if it rocks, and if the shank is square to the same surface. Looks like a nice tool. Mike


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## kd4gij (Mar 5, 2017)

What mill do you have? and how are you feeding?


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## Pontiac Freak (Mar 5, 2017)

Setting flat it appears consistent.  I got a set of 6 sizes.  All are identical.  

Mill is a full size Bridgeport Clone. I have tried feeding with the quill and knee both.  when it bites it bites hard!  Saws are razor sharp on cutting edges.  

Just worried if I cut flats on the shaft it might lock into the drill chuck or break something.


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## kd4gij (Mar 5, 2017)

A bridge port is really dot heavy enough for those cutters. Something with a cat 30 or 40 spindle and er40 collet.


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## richl (Mar 6, 2017)

I would guess the bridgeport is not the problem, it is more than beefy enough to turn those cutters, try another arbor, the round shaft that is on the cutter is causing the problem, the ones I use typically have 8 sides {?}. You should be able to go to any hardware store, lowes, homedepot and pick up one for 10.00 dollars or so that will work fine for those hole saws. Lennox brand are good ones, they have 2 different arbor sizes, they screw into the hole saw cutter. My guess they will work with one of them. I have boxes of lennox cutters I have used or new laying around here, Also 1/2 dozen or so arbors of different makes and sizes.

HTH

Those cutters look like beasts!!! Take care of them, I'm jealous!

Rich


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## British Steel (Mar 6, 2017)

Possibly they jam due to insufficient chip clearance, try drilling a couple of through  holes inside (meeting) the saw's cut to allow the chips out? If you use the saws to 'scribe' the work lightly it'll show you where to drill 

Dave H. (the other one)


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## extropic (Mar 6, 2017)

Make an R8 arbor with a threaded stub to receive the saw(s). Maybe you can adapt/modify a commercially available R8 shank. That's where I'd start looking. What is the thread size for the shank/pilot?

Me thinks those type of hole saws are always going to have the problem of trying to lift the work piece and grab at breakthrough. If your work piece isn't rigid, cover with a clamp plate (MDF w/ a pre-drilled clearance hole)  and lots of hold downs.

By the way, I have same looking cutters but only up to about 1.5". I think they're designed to be used in hand held power tools but on aluminum material (think aircraft). I wonder if the tooth geometry of your cutters is intended for mild steel?


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## AGCB97 (Mar 6, 2017)

To me those look like they're made for wood (coarse teeth). I've used a Starrett saw in steel and it worked good but I think it had much finer teeth than your picture.


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## Pontiac Freak (Mar 6, 2017)

Thanks for the ideas guys, I like the idea of making a R8 Arbor with a threaded stub.  I dont think they are for wood (i could be wrong of course) but the guy I got them from was a machinist for 40+ years and selling all his items.  Wish I would have bought more at the time :-(


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## 12bolts (Mar 6, 2017)

I dont see any "set" to the teeth.
How far into the cut do you get before they start binding?

Cheers Phil


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## Ken from ontario (Mar 6, 2017)

I,d say you have 2 problems here, one is to find or make an R8 arbor for  those cutters, the other is your lubrication. tap & die fluid is probably too thin, maybe you'd get a better performance if you use some paste or solid stick  type that's used for annular cutters.
  I would load up the teeth with the wax  before cutting,see if that helps.
https://www.emisupply.com/catalog/w...nt-105oz-solid-stick-p-2306.html#.WL1QUTsrKLw


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## Tozguy (Mar 6, 2017)

From the original design it does not seem like these hole saws were intended for a lot of torque.
To use on a mill with an R8 threaded arbor would solve the slipping problem but then would those small threads stand up to the torque they might encounter?

What about threading and drilling the hole saw cups to fit a common hole saw arbor like this?
The shank is hex and the keying mechanism takes all the torque so the threads don't take a beating.


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## Wreck™Wreck (Mar 6, 2017)

Drill a hole or two the width of the saw blade through the part at the center of the circles where the blade will cut, this will allow the chips to fall through, a good deal of the binding is the result of chip binding in the cut.

Holding such a tool in an R8 collet is difficult at best.


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## Pontiac Freak (Mar 6, 2017)

12bolts said:


> I dont see any "set" to the teeth.
> How far into the cut do you get before they start binding?
> 
> Cheers Phil


It will bind any time during the cut.  What is the "set" you are referring to?


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## ewkearns (Mar 6, 2017)

These appear to be trepanning tools made for aluminum or wood. The teeth will load up with chips so you are going to have to "peck drill." Unless your pilot hole wallows out, the Bridgeport should be enough mill. What do the arbors mike? Are they undersize?


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## kd4gij (Mar 6, 2017)

Is there a name and or part # ?


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## jbolt (Mar 6, 2017)

Pontiac Freak said:


> It will bind any time during the cut.  What is the "set" you are referring to?



Set refers to the teeth being offset in and out from the wall of the tool. This creates relief above the cutting edge and allows more room for chip evacuation. With the straight teeth of your cutters the area behind the teeth will load up and when the chips have nowhere to go they will bind between the part and the side of the cutter. 

For deep drilling like you are attempting  I agree with Wreck Wreck on drilling some clearance holes. That and taking small step downs with clearing the groove in-between should make a big difference.


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## woodchucker (Mar 6, 2017)

I like he idea of a weldon (kd4gij,) holder, add a flat.. I notice that the teeth are really beefy. So that would definitely take a lot of torque to cut. Not a narrow kerf cutter. So thicker means more power. And that also means its grabbing more. Which means you have to stop that torque from releasing in the collet.  I don't think you can w/o a flat... On wood yes, on metal NO.  I hope you are cutting a hole first for the center. There's no cutting going on there.


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## extropic (Mar 6, 2017)

To the issue of binding, if Pontiac Freak mics the cutter body diameter (ID & OD) I think he'll find a very slight taper  (max at the teeth). There is no "set".

To the issue of lubricant, I would use a pipe threading lubricant by RIGID, or competitor, in this application (slow speed, mild steel).


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## GarageGuy (Mar 7, 2017)

Trying to hole saw a 2-9/16" hole through an inch thick piece of steel just sounds like a bad idea to me.  It's the wrong tool for the job.  If you have a Bridgeport, why wouldn't you drill a hole and work your way up to your biggest drill bit, then bore it to size with a boring head?  It seems like it would be faster, easier, safer, and give better results.

GG


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## tq60 (Mar 7, 2017)

Slipping protects your machine so wait...

How are you feeding?

If by the pull down like a drill press then too much feed means too much power and the collet is exceeded and slips which is better than breaking something.

Use the hand wheel for fine feed and be sure click spring is tight or put up pressure with drill press style feed so it cannot grab.

One rate the "tool" within the limits of the machine and you should be fine.

Sent from my SAMSUNG-SGH-I337Z using Tapatalk


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## woodchucker (Mar 7, 2017)

GarageGuy said:


> Trying to hole saw a 2-9/16" hole through an inch thick piece of steel just sounds like a bad idea to me.  It's the wrong tool for the job.  If you have a Bridgeport, why wouldn't you drill a hole and work your way up to your biggest drill bit, then bore it to size with a boring head?  It seems like it would be faster, easier, safer, and give better results.
> 
> GG


Not much different than using an annular cutter. Is it.


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## FOMOGO (Mar 7, 2017)

A 6" vise is overkill for a RF45 style mill. A 4" is more appropiate for that size mill & IMO 5" max. I have a 5" GMT vise on my PM45 & it's slightly too big. Not enough Y axis travel to make use of the 5" full capacity. Better to save your money rather than getting something too big & most importantly the weight. I take my vise of the table quite often, a 6" is still light enough for me to be carried by hand but I'm glad I have a 5". I also have a 4" vise as well. I prefer the 5" though.

But those GMT 6" Premium vises are pretty nice. I'd love to have one but don't need one on my current mill. But if you plan on upgrading to a full size knee mill in the future than the 6" will be perfect.


Here's what the 5" looks like on my mill.




I couldn't even complete this cut without my bellows & DRO scale getting in the way. Not enough Y travel & the 5" vise is not even maxed out.




Here's what a 6" vise looks like on another PM45 (gt40's)
View attachment 253544


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## Silverbullet (Mar 7, 2017)

Most cutters like these don't really use a set , what they do is grind different angles on some of the teeth . Like slitting saws , some have side cutter and some straight teeth with no set at all. More then anything else I think his feed rate is to fast or hard , also I would recommend cutting oil not tap fluids. If you were cutting hard stainless like 316 I'd use Angkor lube.


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## bfd (Mar 8, 2017)

I would cut 3 flats  on the shank and use a drill chuck (not keyless) and attempt that but as others have noted if you spin the drill chuck in the spindle then you could damage your mill. make sure you are cutting some and backing out and brushing away the chips and cutting some more. there are premade hex arbors for holesaws that don't slip. they get so tight on the arbor that it is hard to unscrew them but they don't slip. bill


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## woodchucker (Mar 8, 2017)

A 6" vise is overkill for a RF45 style mill. A 4" is more appropiate for that size mill & IMO 5" max. I have a 5" GMT vise on my PM45 & it's slightly too big. Not enough Y axis travel to make use of the 5" full capacity. Better to save your money rather than getting something too big & most importantly the weight. I take my vise of the table quite often, a 6" is still light enough for me to be carried by hand but I'm glad I have a 5". I also have a 4" vise as well. I prefer the 5" though.

But those GMT 6" Premium vises are pretty nice. I'd love to have one but don't need one on my current mill. But if you plan on upgrading to a full size knee mill in the future than the 6" will be perfect.


Here's what the 5" looks like on my mill.




I couldn't even complete this cut without my bellows & DRO scale getting in the way. Not enough Y travel & the 5" vise is not even maxed out.




Here's what a 6" vise looks like on another PM45 (gt40's)
View attachment 253544


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## C&I Harry (Mar 11, 2017)

The company Tork Craft at http://www.torkcraft.com sells similar devices. They are specified for sheet metal up to 5 mm thickness. The ones they supply have three flats and are typically used in sheet metal panel work. I have used my 35mm saw to make a hole in a 0.8mm thick 316 stainless steel sink without lubrication and through 3mm mild steel sheet using tapping fluid. Low speed and a steady hand are vital. I recommend the three flat option though I have used mine also on the milling machine using a drill chuck. I have changed my 1/2 " Reduced Shank Drills  to have three flats on the shank for getting rid of slip.


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## Ed ke6bnl (Mar 11, 2017)

I just used a deep cutter to drill a 3/4" hole at least 1" I used a ER32 COLLET and cut like butter. No slip


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## Highsider (Mar 11, 2017)

What you have are good tooling, but they are not hole saws and should never be used in a collet holder.  Hole saws were originally designed with a thin walled barrel and hacksaw like teeth with a set on them which could be used in anything from a portable drill on up.   What you have is a metal cutting tool for cutting holes using a machine tool and which has many times the torque stress while in use, that a hole saw has.  It must be run geared down to fit the load those wider teeth will be imposing on the machine.  Properly used, it will be cutting a continuous chip with each of it's teeth.  The tooth loading and torque arm of these tools require a much more Skookum tool holder than a collet holder.    Chip removal and heat will be more problematic also so try to use large amounts of coolant.  (Preferably through the tool holder you use)   Some of these have a rotating water joint incorporated into the tool holder  which is great for chip removal if the tool has a water passage in it.


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## Rustrp (Mar 11, 2017)

I think the cutter you have is designed for much thinner material. The design allows for cutting material about half the thickness of the tooth depth. There's no place for the chips being removed to go except the gullet. The tooth geometry is such that a lot of material is being removed, plus the surface area contacted by each tooth is 3-4 time that of an end mill or annular cutter. I suspect this tool has or had a special application. It's possible it wasn't designed for steel. Have you talked to the machinist you bought them from? 
Russ


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