Best bit to drill out the guide bar for the mill?

[jimdad07]

I tried to drill out the 28" Dolmar bar I had bought originally to mill and found that that has to be some of the hardest metal I have ever tried to drill out. Now I am waiting on a 30" Carlton bar from Baileys so I can put the Stihl on the mill but I would like to drill the bar and make chain removal a little easier and get rid of the rubber cubes I am using now to hold the bar. The bar doesn't budge a bit on the rubber, but I think how you guys are doing it looks a whole lot easier.

 

[mtngun]

Carbide drill or end mill, low speed.

No, Makita bars are not the hardest metal, Carlton bars are the hardest metal.

 

[porky616]

all i use is the cheap nasty masonry/concrete bits from the local 2dollar shop. step up the hole sizes in stages and throw the bits away when finished. ive drilled stihl bars and gb bars without any drama. oh and i use my little drill press of course.

 

[BobL]

A standard HHS/Cobalt with lube and slow speed (< 200 RPM) and lots of steady pressure (ie drill press) will do 3 - 4 holes without the need for touching up the bit.

 

[Timberframed]

One of these step bits will go through any metal but they are not cheap. You can start the hole with this then finish with a standard bit.

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[mtngun]

A standard HHS/Cobalt with lube and slow speed (< 200 RPM) and lots of steady pressure (ie drill press) will do 3 - 4 holes without the need for touching up the bit.

Not on a Carlton bar, and not thru the nose bearing on any of the bars that I have drilled.

 

[sachsmo]

I used a center cutting carbide end mill to drill the holes in my Carlton bar. they aint cheap, but if you work harden the steel you will be in trouble. Yes drilling through the center of the sprocket nose Carbide would be my pick.

 

[Hddnis]

Cobalt works best and is most likely to cut through without over heating. Masonry bits work because they have the carbide tips.

A good lube/coolant is helpful when cutting any steel and on harder grades it is the only way.



Mr. HE

 

[mtngun]

Cobalt works best and is most likely to cut through without over heating.

I ruined many a new cobalt bittrying to drill through the sprocket bearing (more correctly, the center piece of the sprocket bearing). It would cut through the softer outer metal, but once it hit the bearing material, that's all she wrote.

Cobalt bits do work on the softer bars like Windsor and Stihl (Oregon), but not so well on German Carltons.

 

[BobL]

I ruined many a new cobalt bittrying to drill through the sprocket bearing (more correctly, the center piece of the sprocket bearing). It would cut through the softer outer metal, but once it hit the bearing material, that's all she wrote.

Cobalt bits do work on the softer bars like Windsor and Stihl (Oregon), but not so well on German Carltons.

Cobalt drills have worked for me on the noses of 1 Oregon, 4 GB and 4 Stihl Bars. I don't have any German Carlton bars so can't comment on those. It's critical not to let the tip just ride on the metal - I use 160 rpm, lots of metal lube/coolant and high pressure on a drill press.

Even on just the bar itself I've had less success with Carbide tips than Cobalt. Carbide works for me for one or two uses and then the cutting edges crumble off on the subsequent pass. One Carbide tip has even shattered. Maybe I'm just too ham fisted but it sounds like my cobalts are better than my carbides and yours might be the other way?

 

[Hddnis]

Cobalt is basically a HSS alloy with improved wear properties at higher temps. This is ideal for drills. There may be bearings that are hard enough that cobalt will not cut it, or wear very fast doing so. I have not encountered a bar where this was a problem and I frankly don't remember how many bars I've drilled holes in or what brands they were. I'm not bashing carbide drills at all. I'm using them more and more in my shop just to save time sharpening.

I've thought about replacing my drill press with a small mill, mostly because it will hold tighter tolerances. The X/Y table would be a huge help with a series of holes or hole patterns in fabricated parts. They also cost much more, but I've seen decent used ones for around $1200.00. After that I've dreamed of a CNC table; which would of course run all carbide cutters and basically handle whatever I threw at it. Tools to make other tools sure don't come cheap though.


Mr. HE

 

[willbarryrec]

I drilled a Stihl bar through the sprocket bearing not too long ago...I needed a 5/16ths hole...I tried a few bits and ended up using a Bosch masonery bit from a big box store....I found it helped to keep a slow speed,high pressure and I used some oil just like BobL recommended.

A drill press would be the way to go as far as high pressure but I just used a cordless drill and leaned on it(Not having a drill press).

I also drilled from both sides after using a punch to center the future hole right where I wanted it.

Good luck!

 

[BobL]

One of these step bits will go through any metal but they are not cheap. You can start the hole with this then finish with a standard bit.

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If they are not carbide you won't have a chance with these types of bits. Even with the carbide ones they still require a pilot hole before use and if you succeed in drilling a pilot hole you might as well use a carbide or cobalt bit after that.

 

[Timberframed]

It's the only bit I know of that will go through J2440 stainless & spring steel without effort

[/URL][/IMG] Two 1964 Rockwell 15 -665's They don't make them like this anymore

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[jimdad07]

I have a few vary bits kicking around and a few mason bits, plus I have the drill press with the adjustable belt for different speeds. The new bar I am getting for my Stihl is a Carlton bar. Hopefully between all of them I can get about three holes through it. One in the roller tip and two on the other end.

 

[BobL]

It's the only bit I know of that will go through J2440 stainless & spring steel without effort

Is it carbide?

Two 1964 Rockwell 15 -665's They don't make them like this anymore]

Nice!

 

[Timberframed]

Carbide it is not. But remember carbide is very brittle and won't flex when under certain conditions. These type bits cut from the side. Not from surface contact. Once you're in...watch out!

 

[Fallguy1960]

There called Uni-Bits Bob they are very hard but not carbide. We use them a lot in the electrical trade for drilling large holes up to 1 3/8". I have used the same bit for over 5 years. It is best to use pilot hole to start them though.

 

[BobL]

There called Uni-Bits Bob they are very hard but not carbide. We use them a lot in the electrical trade for drilling large holes up to 1 3/8". I have used the same bit for over 5 years. It is best to use pilot hole to start them though.

I have a cheap chinese one that I use for up to 12 gauge sheet metal but it won't work on anything harder than mild steel. i have also see a carbide version but it was very expensive.

 

[Sawyer Rob]

Two 1964 Rockwell 15 -665's They don't make them like this anymore

You will have to look long and hard to find one like this these days too! A high presion drill press made in Sweden by Solberga Mekaniska.

With it's all gear transmission, with gear selectors to change speeds, and your choise, power or maunal down feed. You also can select different power down speeds, for tapping holes with a foreward/stop/reverse foot control... This DP is absolutely one sweet precision machine!

It has MUCHO power, and it easily bores 3" holes! Maybe even bigger, but 3" is the biggest i've bored so far.

Rob