[Spartan]

Had to make a mod to the scope rings on an airgun, and decided to get some video of it for a little hobby-hunting channel I started on YT. Figured I'd share it here as well since it is machining. The scope cam footage at the end is neat if you've never seen that type of thing.

Warning: The video contains images of airguns, shooting, and talk about guns. If you don't like that sort of thing, then please do not watch the video.

https://www.youtube.com/watch?v=n2BMMx8luzU

[TraditionalToolworks]

I've done a similar project modifying some rings in the past. If you didn't use any cold blue, try some Oxpho-Blue from Brownell. Pretty easy to use.

[BugHunter]

At around 3:50 you mentioned that you felt chips were being deposited back on the part when you climb Mill. Thing is you were conventional Milling at the time, climb Milling is what you use to put on a nicer finish. In all truth, tools will live much longer if you do all operations climb Milling. The Mantra is, start thick end thin. Meaning when you climb Mill, the tool will cut more when it starts the cut and tapers off to nothing as it exits the part. That is much easier on the tool and actually easier on the part. When you conventional Mill, the amount of heat generated is dramatically higher because the tool has to smash its way into the part in order to start cutting. That's why you get more chip weld that way. The tool pressure is sometimes an order of magnitude greater and the friction is obviously also far greater.

[TraditionalToolworks]

I disagree with Buggy.

Climb milling should be avoided on non-rigid mills. Spartan's mill is really not the best to climb mill with.

If it handles it, go ahead. I would avoid climb milling and stick to conventional milling. I was going to mention that, as he goes back and forth, I would only mill from left to right or rear to forward depending on the side your milling and having the mill turning in the clockwise rotation.

Not my mill, not my tooling, yada-yada-yada...

[Spartan]

I've done a similar project modifying some rings in the past. If you didn't use any cold blue, try some Oxpho-Blue from Brownell. Pretty easy to use.

Yeah, I was wondering what to do about that since the rings were originally anodized. I typically don't hunt in the rain so figured I could just leave it as is without any issues. Also can't really even see much of the bare metal when everything is mounted up. I wasn't aware that bluing like that would even have an effect on AL. I'll have to play around with that.

At around 3:50 you mentioned that you felt chips were being deposited back on the part when you climb Mill. Thing is you were conventional Milling at the time....

Yup! I realized in post (actually the final review after rendering) that I had misspoken there. Should have added a little pop up text thingy correcting that.

Climb milling should be avoided on non-rigid mills. Spartan's mill is really not the best to climb mill with.

If it handles it, go ahead. I would avoid climb milling and stick to conventional milling. I was going to mention that, as he goes back and forth, I would only mill from left to right or rear to forward depending on the side your milling and having the mill turning in the clockwise rotation.

Agreed. That is the typical MO for my mill. However, taking light passes on AL as I was doing there seems to go just fine.

[Ballistic308]

I've done a similar project modifying some rings in the past. If you didn't use any cold blue, try some Oxpho-Blue from Brownell. Pretty easy to use.

I think you meant Aluminum Black, since the part is aluminum and not steel.


BW Casey Aluminum Black Touch-Up 3Oz https://www.amazon.com/dp/B002JCW2CG/re ... xFb0Y615R1

[TraditionalToolworks]

Agreed. That is the typical MO for my mill. However, taking light passes on AL as I was doing there seems to go just fine.

With alu you should be ok, but just be warned and especially with that long end mill you were using. Most likely will be a broken end mill, they tend to snap off pretty easily. To be fair, Buggy is right in the sense that it is the best finish, but even when I do climb milling I tend to only use it for a very light final pass, and my mills are much more rigid than yours.

I think you meant Aluminum Black, since the part is aluminum and not steel.

BW Casey Aluminum Black Touch-Up 3Oz https://www.amazon.com/dp/B002JCW2CG/re ... xFb0Y615R1

Yes, actually you're right, and I think that's why I have that product also...but don't care for it much...but now that you mention it I don't believe Oxpho will blue aluminum, I think it needs to be steel. I'm pretty sure that's why I have that.

I do use Oxpho-Blue on steel and have done entire mobile bases and carts in it.

I will say that most of the cold blue products don't penetrate as well as one would like and often show variance in color. Prep is key in using them. I've tried heating with a heat gun, but get similar results.

Cerakote would probably be a better choice, if someone has an oven to bake it. DuraCoat has a spray on blue product also, but I haven't used it. Not cheap, but neither is Cerakote. Might be able to just spray it black, not sure how that would hold up.

[BugHunter]

I disagree with Buggy.

Climb milling should be avoided on non-rigid mills. Spartan's mill is really not the best to climb mill with.

Climb milling is going to make the tool last arguably 10x as long, if not longer. Ultimately, it's actually easier on the machine. Now, using a mill the size he used there in a machine the size of that machine, isn't the best combination. But done using a little common sense, it's fine.

I have a toolroom mill here (an XLO) and it's got loads of slop in the lead nuts. Might be .100". It's still ok as long as I keep tension on the gibbs to a point where it won't drag the table/part into the tool. IOW, you can 'make' the machine rigid if you want to. Lock one gibb, tighten the other till it holds the table securely but still allows it to travel, and go cut whatever you want.

PS, when I cut almost any material, I cut 1/2 the endmill diameter per pass. (assuming there's that much material to rough off). That makes for an ideal tool starting cut and hence, more tool life, less heat input, better chip evacuation, and actually less stress on the machine. In his situation, I would have chosen a 1/2" carbide endmill with 1.5" loc, and would have never run the part left to right while cutting.

I'll draw a pic in autocad and post that for clarification.

[Spartan]

In his situation, I would have chosen a 1/2" carbide endmill with 1.5" loc, and would have never run the part left to right while cutting.

I think I own a grand total of 7 end mills at this point, so my options were a bit limited.

That was the only one I had which was long enough to make the cuts in that configuration.

[BugHunter]

In his situation, I would have chosen a 1/2" carbide endmill with 1.5" loc, and would have never run the part left to right while cutting.

I think I own a grand total of 7 end mills at this point, so my options were a bit limited.

That was the only one I had which was long enough to make the cuts in that configuration.

Lol, well, we've all been where we didn't have the ideal tool for the job. Happens all the time.

Here's the image of what I'm talking about.

On the left, conventional milling, you can see how when the tool enters the part, it has to slowly go from not touching the part yet, to cutting a super-thin layer, and ends with a full cut. Full meaning, whatever the amount of advancement of the cutting axis per rev / cutting edge of the tool, that's the nominal cut depth.

On the right, climb milling, the tool beings the cut with whatever that amount of advancement is and instantly cuts full depth of material, then the cut gets easier as the tool progresses through the 90 degrees of cut.

Conventional milling, the tool rides over top of the part until it has so much tool pressure the tool is forced to cut something. Not only is there massive friction, there's massive friction IN THE PART.

Climb milling, The lion's share of the friction is captured inside the chip being removed. The part has almost no friction on any bit of it that remains after the cut. The tool has dramatically less friction because it wasn't smashed into the part. It CUT the part, it didn't whittle it. This way of starting a cut does not rub the cutting edge of the tool, wearing away from the positive rake on that edge. That's why they last virtually forever that way.

FYI, I have 1/4" carbide endmills in my toolbox here that have been used for literally 15 years on a week to week basis, and they still cut very nice. Not like new, but let's be serious. that same endmill wouldn't last a week (sometimes not a day) if it had ever conventional milled.

[Spartan]

Great info to have, Bughunter! Thanks for sharing that. Wasn't aware of the long term effects cutting direction could have on the tooling.

[BugHunter]

Unfortunately, in the home hobbyist world, many people never get exposed to design specs of tools or default set ups for machines. Additionally, often times they avoid the actual design specs of tools because most times their machine does not have the performance to achieve those feeds or speeds. So they work within what they feel is right for their own machine, which is more or less correct, but definitely not optimal.

If you ever get into carbide insert tools, which I'm not particularly recommending, and you actually read up on what they intend that tool to do as far as metal removal rates, it will blow your mind. Tool companies research long and hard about how to get the maximum amount of metal removal from a particular tool. So when you see a speck of cut depths and feed rates, and at what RPM's they recommend as far as surface feet per minute, you soon realize that Holy Smokes, I need massive horsepower and big RPMs to even do what they are asking. And then I'm going to have to hide in the next room because of all the stuff that's coming off the part. LOL

At work I have a 6 inch lathe with 15 in between centers and a 15 horsepower direct-drive spindle, and it won't run fast enough and doesn't have enough horsepower for some of the tooling that I run. The same manufacturer, Okuma, makes a next model up 8 inch lathe with a 60 horsepower direct drive spindle, and that one has a default roughing cut using an 80 degree 1/2 inch IC insert, of 1 in per pass. That's a half an inch of cut depth per side, by default.

I did work for a place years ago and talked to some of the tool Engineers there, I worked on the machine controls which of course had cumulative tool use data which they stored. I remember operations in production using Guhring drills where a drill had drilled more than a mile of Steel. It's just a testament to proper coolant, proper feed speed for the particular material, proper RPM's for the drill diameter. Everything matters. It's the difference between buying drills by the gross or buying one and using it until you retire.

PM me your address and I'll send you a couple really nice end mills. But you have to promise not to ever conventional Mill with them. LOL there's no sense in using them once and throwing them away.

[TraditionalToolworks]

At work I have a 6 inch lathe with 15 in between centers and a 15 horsepower direct-drive spindle, and it won't run fast enough and doesn't have enough horsepower for some of the tooling that I run.

Who's the hobbyist here?

I mean you can't get carbide to run on that?

That 15HP motor must be spinning at a snail's pace...probably not enough power to run negative rake tooling either...

[BugHunter]

Who's the hobbyist here? roll:

Oh, aren't you just the funny guy...

I mean you can't get carbide to run on that?

Learn to read what I said. To meet the tool manufacturers recommended optimal metal removal rate. I'd say it's pretty obvious you've never bothered to read the data sheets but that's okay, if you actually calculated the spindle speed and feed rate required to get to their recommended numbers, you're not going there anyway.

That 15HP motor must be spinning at a snail's pace...probably not enough power to run negative rake tooling either...

Your ignorance is showing. Yes, under certain circumstances which are far more typical than you seem to understand, yes it is far too slow. That is why they invented something called a Swiss lathe. (Swiss screw machine)

[TraditionalToolworks]

I had a reply to this, but decided not to send it.

Suffice to say that your implication that home hobbyists don't know as much as you is utter BS. You might be a welder, but that's a far cry from being a machinist. Some of the best machinists I have had the pleasure to meet would be classified as home hobbyist.

[Poland308]

I had a reply to this, but decided not to send it.

Suffice to say that your implication that home hobbyists don't know as much as you is utter BS. You might be a welder, but that's a far cry from being a machinist. Some of the best machinists I have had the pleasure to meet would be classified as home hobbyist.

Bit sensitive?

[cj737]

I mean you can't get carbide to run on that?

That 15HP motor must be spinning at a snail's pace...probably not enough power to run negative rake tooling either...

Toolie, you do realize he’s describing an Okuma CNC lathe spinning at up to 4,500 RPMs right? Ive seen lots of tooling (especially insert cutters for CNCs that are “prescribed” to run at like 25,000 RPMs. I think that was his point. Despite what manufacturers state, we often have to make do with what we have available to us, or feel comfortable with.

On my lathes, I’ll spin much slower because (right or wrong) I feel like it will prolong life of the tooling or I just can’t get a rigid enough hold of the piece. Besides, I don’t do production work on my mill or lathe so time is less critical than tooling costs.

Just saying, I think Bugs is on point with his post.