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

[BobL]

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

The other thing that's "gold" on that machine is the 120 RPM speed.
Oh yeah the BIG table is pretty nice too.

My DP has a 1 kW motor and can reach 160 RPM and drill 2" holes in mild steel but every now and then I could have used more.

 

[bobsreturn]

nice drill used one years ago sure have to locate the drilled piece well as no belt slip , not like a lot of chinese rubbish sold today , cheers Bob :chainsawguy:

 

[Ptarmigan]

Drilling with end mills

So, I've been following this thread because I'm setting up a mill, (homemade 80/20 build w/ a 394 to power it) and have waited for a month or so for my new bar to arrive. The brown truck came by yesterday afternoon and dropped off the new Oregon 37"er.

Today's my day off so I thought I'd try to see what worked best for me. I don't have access to a drill press, only a 18v dewalt. I have a set of HSS bits, Cobalt bits, and some 1/8 and 1/4 carbide end mills from a previous rifle project.

I decided to tackle the sprocket first. After punching a center mark I went to work with the HSS at 4mm size. I lubed generously with cutting oil and using slow speeds and a fair amount of pressure... It cut through the softer outer steel OK but going was slow and really slowed once I reached the harder center bearing steel. I switched to an equivilent cobalt bit and the going was about the same. As I was pushing I remembered the end mills and thought I'd give an 1/8 ball end mill a try. With pretty heavy pressure, alot of lube, and slow speeds (really light on the trigger of the drill, almost as slow as it will go)it went through the hardened steel at a pretty quick clip. I then used a 1/4" chipbreaker ball end mill to enlarge the hole and that went through nicely, also with pretty heavy pressure, real slow speeds and alot of lube.

The holes through the mount side of the bar were actually pretty easy after doing the sprocket side.

Thought I'd share this with everyone... you can find ball end mills for about 6 - 8 bucks online and they seemed to work alot better then either of the drill bits I tried.

Sean

 

[jimdad07]

My new Carlton bar came in today along with my milling loops and files. We have two children under four that my wife is home with all day, she sprints for the door some days when I pull in the drive... so, as soon as she gets home from a trip to town with her mother to get programmed, I am going to give it a shot with an assortment of masonry bits and do it in steps. Let's hope.

 

[jimdad07]

I drilled out the Carlton bar tonight by setting my drill press down to 620rpm and first drilling a pilot hole with a 1/16" inch bit to keep the mason bit I was trying from wandering on the hole. Used good ole WD-40 for lube/coolant. Immediately stepped up to a 1/4" masonry bit to do the end of the bar nearest the saw. That one took about ten minute with steady pressure on the bar from the press, not forcing it too much and a lot of lube. The hole in the center of the bearing was done with a pilot hole (1/16") and finished with a standard 1/4" titanium bit. The nose end went through very easily, was not nearly as hard as the bar.

 

[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.

I tried drilling a hole in a replacement Oregon nose bar last night using a Cobalt bit and got nowhere. I resharpened 4 times and got nowhere so I gave up and had to use a carbide bit and it took ages. I'd say it was the hardest nose I have ever drilled, much harder than the Stihl or GB bearing material. It seems like there are "bearing materials" and "BEARING MATERIALS".

 

[DRB]

I have had the same problem with oregon bar tips as well. The bear material is definitely harder than the bar.

 

[jimdad07]

One of the old timers I work with in the steamfitters union swears by using Windex for a coolant, he swears you can drill anything when you use that. I guess he uses it when he's drilling stainless steel with HSS bits.