My second DIY mill (pictures)

[Andrew96]

Guys. I'm more of a reader here but found so much that it's time for me to show off my second mill. Of course. It's a bit bigger. I don't need to tell you how much fun pictures are. It's not done yet. The photos don't show the safety wire keeping the fasteners on (read about BobL shooting himself with his nuts)...nor the handle which isn't done yet (still working out a good method to damp vibrations). So...my mill summary: Based on 36" 404 0.063" bar converted to 3/8 tip powered by a 660. Clear 29.5" of cut. Made from thin wall 3/4" HSS tubing. Strong enough to support everything without bending. I haven't put it on a scale yet but it doesn't feel as heavy as it looks. The balance point is about 6" in from the roller so it will stay stuck on the top of a log without help. It's a bolt through the bar design (grade 8 bolts drilled for safety wire) so you can remove the chain without disturbing anything. Tip is bolted through the bar rather than onto the tip or through the tip to catch the end of the bar and not overly load the rivets holding the tip on...at the expense of loss of cut width. Depth adjustments are done by moving the pin to another set of holes in 1/8" increments (Difficult indexed drilling job to do both posts the same...and get the dim correct including the Kerf). No tools required to change dims. You can see the stamped dims on the upright...though you cannot see my other reminder on the inner post...inch increments. Those are just stamped, then painted so I can read them...hopefully for awhile...hence the white/black paint. The tip guard protects the tip when I sit it on the ground so I can lay the assembly down to fuel and oil without sticking the chain on the ground. Of course...also I don't cut anything on the other side of the log I didn't intend to cut..including someone elses leg. Of course, rollers (ate up the last 1/2" of bar length). The extended end rails can be used for any future extension, future extra oiler, ...but for now..I can stand the assembly up on the tip..without actually loading the tip of the bar. Hopefully will get the handle sorted this weekend and maybe even give it a go if the weather holds. For me....29.5" of cut is a lot right now. So..there you go...enjoy another home built mid sized mill (maybe a baby to you). It's got it's limitations....but OK for me now. I don't seem to find the huge stuff some of you guys do.

 

[Ollbuster]

Nice mill, quick question how do you drill the quide bar? I tried it once with every drill bit I could find and had no real luck...

 

[mtngun]

Re: drilling bars. Some bars are harder than others, but in general carbide is the way to go. I use a centercutting carbide end mill.

 

[chuckwood]

use cobalt drill bits

Nice mill, quick question how do you drill the quide bar? I tried it once with every drill bit I could find and had no real luck...

I've done it using a drill press, oil, and a cobalt bit, go slow and easy. Anything other than cobalt won't cut it....

 

[Ollbuster]

I tried cobalt on my stihl bar, just smoked it, thought I was going slow and used lots of oil. I might try it on my other bar and see if it is any softer. Thanks for the tips.

 

[Daninvan]

I've drilled three different bars (all for Husky saws) each with two holes in them and had no problems.

Like the other said, drill press, carbide bit, oil, slow. I also use a centrepunch to prevent the bit from wandering at the start. I clamp the bar securely to the drill press table with a piece of hardwood for a backer, and support the other end for long bars. Often times the bit will leave quite a large 'rim' on the backside of the hole where it comes through. This I grind off.

If you are going to thread the hole afterwards, put the tap into the chuck of the drill press and turn it by hand to thread the hole. Using the drill press will keep the tap square to the bar and so your threads will be nice and straight. I strongly recommend unplugging the drill press before you do this to prevent any problems.

Good luck!

 

[dave k]

Very nice Andrew uncomplicated and I like the wheels.
Did Bob get hold of you ?


Re drilling bars I use the method suggested by Mr Malloff, I use a good standard bit but place the bar Im drilling on another bar which absorbs the heat generated stopping the bar hardening as you drill.

 

[BobL]

Nice work Andrew, it looks good and tidy and a very clever indexing system too.

I'm surprise to see you don't have some sort of cross bar handle on it - it will be quite awkward to maneuver without this - also it means you need to bend over more than you need to.

I also can't work out how it accommodates different size bars?

It's a bolt through the bar design (grade 8 bolts drilled for safety wire) so you can remove the chain without disturbing anything. Tip is bolted through the bar rather than onto the tip or through the tip to catch the end of the bar and not overly load the rivets holding the tip on...at the expense of loss of cut width. .

I wouldn't be worried about overloading the rivets on the nose. The forces in milling are not like on cross cutting. Bar noses are made to take a fair bit of punishment such as where the nose can get jammed and operators twist the bar to break free. All the forces in milling are in the forward direction which the bar can take quite easily. Bolt thru nose is also a bit safer as well.

Anyway - you guys know me so can take all this with the usual grain of X!

 

[Andrew96]

Thanks for the nice comments guys. BobL, I don't have a handle yet. I thought of just a cross bar but was dreaming of some sort of rubber mount. I can't seem to find what I want so I might do something else. I'm not keen on the straight across bar (though right now it's the best option). Height + you can move your hand around...wrong angle for my hand I think. We'll see. I think this will be my everyday rig. 30" is quite a lot for me. When (I don't think it's an if) I make a bigger one, I think I'll go through the center of the roller nose, or use a solid bar. You cannot see how it can handle a bigger bar because it can't right now. The frame extensions will allow me to dowel pin on a rail extension if I choose to use the same rig (of course an additional upright is already made). However, I've already started to think of a longer one and would like some different features. Support the power head, ability to twist the bar to control bar sag, extra oiler. I don't need those features on such a short bar.
I thought the issue of drilling a hardened bar might come up. That was easy compaired to the indexed uprights (accuracy in many planes). There is little margin for error so you better get the details correct. I used standard HSS bits, and a center bit, on a drill press of course, wood backer, clamped, cutting fluid for coolant. Now...I get to cheat a bit. I use a Drill Doctor sharpening system so I can create perfect geometry on my drill bits and choose what geometry I want for the application. The holes were a non issue. It is hard material, but a slow surface speed is required since 'if' you overheat it...you're done for. I think I ran the 1/4" at 500rpm. The 1/8" from about 1000rpm. The bit should never get hot enough you wouldn't want to hold it in your fingers, if it is, slow down, flood with coolant, hope you can still cut the remainder. I step drill as well on difficult things like saw bars. Those are only finished 1/8" and 1/4" holes so 2-3 steps will get you up to size. No heat is the key..oh, and a perfect cutter. Just like a beautifully sharp chain...judge your drill bits performance by the type and shape of your chips, don't force the cut and take 20 seconds to let it finish without forcing it.

 

[sctstoys72]

concrete bit, carbide tip, get"em anywhere

 

[Andrew96]

DaveK sent a PM. Read it.
There are lots of ways to drill a hole. It is btw..just a hole.