These bars are tough stuff!

[4x4American]

I've been trying to drill a 7/16" hole through my rollomatic es bar for the past hour now with a brand new cobalt bit. been going slow and keeping the bit very well lubricated with new 5w-30 engine oil...so anyways...I hit a point where i just cant get it to drill anymore I've been putting so much pressure on it and it won't do nothing. I got to kicking myself in my rear for not drilling a pilot hole. So I tried drilling a 3/16" pilot hole after the fact to no avail. So now I'm thinking about going back to home depot and looking for a diamond or carbide bit. If I find them should I get one to drill a pilot hole with too? I've been using a drill guide too, it's made by general tools...if you ever see one of these in the store be sure to avoid it they are complete junk, there are good ones out there but proberly have to special order them online. I have almost everything I need to make my own chainsaw mill I was hoping to be milling tomorrow but at this point I'm not too sure.

 

[Freakingstang]

Drill press and pilot hole are a MUST... slow speed, lots of pressure and oil

 

[mtngun]

You've probably work hardened the bar metal at the spot where you were trying to drill.

Carbide is the way to go for drilling bars, especially if you drill through the nose bearing, which is harder than the rest of the bar.

Pilot hole not necessary if you use carbide.

 

[mtngun]

If you don't have cutting oil, use bacon drippings.

 

[4x4American]

You've probably work hardened the bar metal at the spot where you were trying to drill.

Carbide is the way to go for drilling bars, especially if you drill through the nose bearing, which is harder than the rest of the bar.

Pilot hole not necessary if you use carbide.

thank you. yes i'm drilling through the sprocket. I'm going to run to home depot and try to find a carbide bit.

 

[4x4American]

Drill press and pilot hole are a MUST... slow speed, lots of pressure and oil

I wish I had a drill press, but I don't so I got a drill guide in an attempt to keep it straight, but it's such a crappy drill guide it was the only one I could find after calling all over, I took it. It's almost better to have done it free hand.

 

[aarolar]

I wish I had a drill press, but I don't so I got a drill guide in an attempt to keep it straight, but it's such a crappy drill guide it was the only one I could find after calling all over, I took it. It's almost better to have done it free hand.

You won't find any carbide at HD or Lowes and I will be willing to bet a carbide drill bit won't last you 10 seconds in a hand drill or cheapo drill press. Carbide is a very brittle material and unless used in a very rigid machine (ie good drill press or milling machine) the sharp cutting corners of the bit will chip off very quickly leaving you with a very heavy expensive paperweight. My suggestion is to bite the bullet and find a machine shop in your area, chances are they won't even bother to charge you for such a simple task as long as you are polite and not in a hurry...

Just for future reference you are right to use plenty of oil but going slow can mean many different things. You need to turn the bit slow but keep plenty of steady pressure, turning the bit slow with light pressure is worse that turning the bit at high speeds.

 

[4x4American]

You won't find any carbide at HD or Lowes and I will be willing to bet a carbide drill bit won't last you 10 seconds in a hand drill or cheapo drill press. Carbide is a very brittle material and unless used in a very rigid machine (ie good drill press or milling machine) the sharp cutting corners of the bit will chip off very quickly leaving you with a very heavy expensive paperweight. My suggestion is to bite the bullet and find a machine shop in your area, chances are they won't even bother to charge you for such a simple task as long as you are polite and not in a hurry...

Just for future reference you are right to use plenty of oil but going slow can mean many different things. You need to turn the bit slow but keep plenty of steady pressure, turning the bit slow with light pressure is worse that turning the bit at high speeds.

Thank you for your input. At home depot I found one Bosch 1/4" carbide bit that was meant to be a pilot for hole saws so I got it, and sure enough it went right through it. I have a drill press at work I could do it there monday, but if I find a carbide bit tomorrow I'll proberly take it to the farm and do it there on my other bossman's drill press. And yes I always keep steady pressure at slow pace with oil, as with drilling any steel. I drill through cold roll steel at work on a frequent basis it ain't like I've never drilled before, it's just that I don't have the right tools for the job here at home.

 

[hamish]

Whatever you decide to drill with watch your speed and pressure, adjust according to your chips.

MMMM Bacon, thanks Dan 1130 at night and the fry pan is going on the stove, mmm bacon!

 

[LegDeLimber]

Now that you've got a pilot hole , if a larger bit isn't practical,
you might consider working the hole out with a chain file or
chain grinder stone.
Sometimes ya just go a little ghetto fashion if availability
and the budget or time constraints demand it.

also, carbide burr in the dremmil might be easier
to not have it grab and snap.

What I should say is think about how a drill bit will grab as it's breaking through to back side of what is being drilled
It gets to about half diameter ,
then the flutes catch on the "burr"and pull it through
sorta like a wood screw till it stops at the end of the flutes
then either spins in chuck or snaps.
if you have a scrap of metal and extra bits to practice with,
you can see how it grabs and decide what's best for you available tools.

also forgot: that break out point also a bad spot for snapping the corners of the tip of a bit.

 

[john taliaferro]

Clamp a piece of mild steel on the back side and drill threw the bar into it . SLOWLY with oil. :hmm3grin2orange:what ya milling ,got pictures?

 

[4x4American]

Welp I got sick of driving all over looking for drill bits. I'm going to stop by Grainger tomorrow and see what they've got. I have a quarter inch protection plate behind the guide bar that I plan on drilling into for a little bit after the bit goes through the bar. Here's a picture of my setup for drilling. I need a bigger work bench I know, once I get the mill going I'm planning on building myself a little shop shed out back.

View attachment 265186

 

[cityslicker]

Are you drilling directly through the center of the sprocket tip bearing or just outside of the sprocket? If through the center is there a void in there? I have been considering bolting my bars to the mill rather than clamping them but I am not sure where to drill on my Stihl ES bar. Good luck and thanks for posting your lab test results!

 

[Cedarkerf]

Clmb up on the bench so you can put real pressure on your drill or mount it on the floor, were talking real pressure here not just firm.. Arm pressure at that height aint gonna cut it. Ive hand drilled a lot of Inconel,titanium and cres fixing jets. You need leverage to get real pressure on a drill or your just abraiding the edge.

 

[BobL]

I've never been able to drill one with a hand held drill as I just cannot seem to get enough pressure.

I use a masonry bit on a drill press with a slow speed and high pressure. Sometimes it has take two bits to get through but haven't found one that has defeated me yet.

 

[bigmoose]

I have drilled dozens of stihl bars. They will work harden. I have never drilled the sprocket. I have spot anealed the hole when they work hard but u cant heat the sprocket. I have used countersinks to finish hardened holes they cut great. If you had drilled a pilot hole you could flip it and go from the other side.


MOOSE

 

[sachsmo]

Go to J&L MSC or other cutting tool suppliers.

Get a center cutting carbide end mill of you size.

Go slow, really slow right before breakthrough.

 

[4x4American]

Thanks for the advice everyone!

A coworker told me that his son works at a machine shop and that I could give him the bar and he'll finish the hole in the sprocket for me and cut the other hole. When I used the drill guide, the 7/16" cobalt bit kinda walked around a little bit and made the sprocket hole wider than it should be, should I have the machinist make the holes 1/2"? I think that the I.D. of the sprocket is 1" so there is wiggle room. I am thinking that will be the best route to take. Maybe even go 9/16"? I think I'll measure the bar and see how big he can go without touching the rivets, and then have him drill the biggest hole possible.

 

[BobL]

Maybe even go 9/16"? .

Why such a big hole? Most of my bars (including the 60" bars) are drilled with 6 mm bits, that's a fraction under 1/4". If you use a high tensile bolt it work fine.

 

[4x4American]

Why such a big hole? Most of my bars (including the 60" bars) are drilled with 6 mm bits, that's a fraction under 1/4". If you use a high tensile bolt it work fine.

to cover my screw up, when I was trying to drill with a pos drill guide the bit walked around and made a larger hole than I wanted. I just measured it, if I step it up to 1/2" it should cover it. The hole right now is 1/4" and has a 7/16" countersink and it's egg shaped all one the side I started drilling from and the exit hole is a very nice looking 1/4" hole perfectly centered between all the rivets. If I only I had the right bit...oh I talked to graingers today too, the carbide bit in 7/16" x 4.5" long would cost me 96 bucks. I said I only need a carbide tip and she said they didn't have anything like that I said thanks anyways.