My First Post here ,A Simple Question for the Enlightened

[Jackotrades05]

Hello All, First Post, so ya know,

I am drilling into an aluminum rod for practice for now until I get confident enough to use stainless.
It is 1" dia. and I am building a unique style muzzle brake , It is for .22 cal. so the out hole will be 17/64" , that's about as tight as I wanna go ,some go to 1/4" ,but maybe in My next life I will too.
The threading will be 1/2"x28tpi ,and the depth of the hole .400" , so it should fit most all My target 22's .
I was wondering what type drill bit to use for the short bore at the muzzle end ,by the way the total length will be 2-3/4" when finished , if I can get the hole centered ,any Ideas on how to get a Precise center without spending more than I can buy a Factory compensator for.

If Incomplete on the specs , it's because I have been working on this for about 2 mo. now ,and I had to get away from tools for awhile.

Thanks, Jimmy

[Harold_V]

Hello All, First Post, so ya know,

Welcome to the board!

I am drilling into an aluminum rod for practice for now until I get confident enough to use stainless.

If you are a stranger to machining, that may be useful, but if you think machining aluminum will aid you in machining stainless, you're in for a rather unpleasant surprise. Surface speeds for aluminum border on not being important. That's not true of stainless, which can get you in trouble quickly if you run too fast, or if you don't feed properly. Not trying to discourage you in any way, just a heads-up that working with stainless is going to be far more challenging than working with aluminum.

You can minimize the negative aspects by making wise selections of the stainless alloy, by the way. There are three alloys that should be reasonably available to you. Two of them are almost identical, one being 303 S, the other being 303 Se. The sulfur (S) or selenium (Se) that is added alters the cutting behavior of the material, making it much easier to machine. The third choice is 416. It, too, is a free machining grade, and is the nicest of the three to machine. It can also be heat treated, unlike the two 303 alloys, which are non-magnetic in the annealed state. They can be hardened, but it's accomplished by cold working.

I was wondering what type drill bit to use for the short bore at the muzzle end ,by the way the total length will be 2-3/4" when finished , if I can get the hole centered ,any Ideas on how to get a Precise center without spending more than I can buy a Factory compensator for.

One has few choices when working with metals. Twist drills are commonly used, but don't necessarily provide for straight or round holes. It should be noted that how one starts the hole makes a difference. Old shop practice dictates that a center drill be used to locate the hole before drilling. They are short and rigid, and will drill where pointed, unlike a twist drill. If hole size and location is critical, an undersized hole is generally created, then bored to size, which ensures a straight and round hole, on proper location. That can be difficult with small diameter holes, but you always have the option of reaming for size.

Reamers still offer the opportunity of yielding holes that are not round (tend to be multiple sided, according to the number of flutes of the reamer), but they generally will yield quite straight holes. The error in roundness is generally quite small, and may or may not be obvious, if it exists. To ensure the hole being properly located, it's common for the machinist to drill undersized, then to bore the small hole a short distance, to establish location. It can then be further drilled to the size required for reaming. You also have the choice of using a spade drill, or a gun drill, although they are not typically found in the shop. Each has a potential to yield holes that are straighter than holes generated by twist drills.

In regards to establishing the proper relationship of the hole with the other features, it would help if you posted a picture or drawing of the muzzle brake. There may be an alternate method to the approach. One of them might be to establish the hole first, then to machine all features by running the part between centers, using the hole. That would ensure you were concentric and in the same plane.

Hope some of this helps.

Harold

[hammermill]

welcome to the forum.. it may seem presumptious but you do have a lathe???

[Jackotrades05]

Thank You Very Much,
You have given me much to ponder , and study ,the thoughts are a lot clearer when I stay out of my workshop for a few days ,and come back fresh with a new attitude , and sense of direction.
The fact I am only working with a new drill press ,and am really getting a chance to use it whenever I like ,and not when my Father would come down the stairs as a boy ,and give me hell for ruining his tools.

Now all is mine ,little that it is , so sometimes I have to remember I'm not that kid anymore ,at least in public!

Thanks again , and I will post sketches asap to this Thread.

Sincere Thoughts , Jimmy The Kid,SEMPER FI !

[Jackotrades05]

Hammermill ,No I do not yet own one , but when I can afford one it will be one that will last My Grandson's curiosity

Jimmy,

[Jackotrades05]

O.K. Harold, I'm Packed , and ready to face the Beast again.
The Wife packed me a large camping Bag O' Grub , so it's Back out there to face the critter once again, it's 75 ft. from the house ,but she had that look on her face like I was going ahead of the trail to scout out some rough Country somewhere in the Yukon Territories , and wouldn't be back till the Spring thaws !

Later On , Jimmy

[Jackotrades05]

Back to the TVset , these are center drill bits from Grizzly , how do you think they will work in a drill press?
http://www.amazon.com/Grizzly-H5931-pc- ... d_sim_hi_3

I was lookin thru the catalog ,and they were half price at Amazon.

Best , Jimmy

[Harold_V]

Back to the TVset , these are center drill bits from Grizzly , how do you think they will work in a drill press?

They'd work just fine for drilling, but if you make the selection the 60° variety, they'd double for drilling centers when you want to run parts in a lathe. For some reason, that's what I figured you had when you talked about making a muzzle brake. That's not to say it can't be done with just a drill press, but it's going to be somewhat more difficult, for many reasons. First of all, I've rarely seen a drill press than had a table that came even close to being at a right angle to the column. They often lean front to back, which isn't typically an adjustment that you can make to correct the error. That's critical if you drill distance and hope to have the drill end up where you'd like it to be.

Back to the center drills, unless you figure on doing some pretty large work, you might be better served to buy just a couple of them. A #2 and a #3 would serve your needs pretty well, as you don't have to make the starting hole very large, just large enough for the web of the drill in use to not cause the drill to wander, which is a common problem. The only exception I'd make here is if you intend to do some small work, then a #1 would be a nice addition, but, be advised, that small point is very easy to break, in particular if your chuck doesn't run true, and they rarely do.

Center drills, given the opportunity, will drill on center if you hold them by just a short amount, and don't get down on the chuck wrench too hard---it should be free to wander slightly. When it makes light contact with the part, of will often move to center. If it's gripped rigidly, that can't happen.

If you intend to use a drill press, it would pay you to do a few things to ensure that the part stays where it's desired. A small vise is pretty much advised, but you should also clamp the vise rigidly to the table once you have it located properly. That will prevent movement when you have to use both hands for other functions. That's particularly true if you hope to have a straight hole, for if you move the part too far off center, while the drill will drill the hole, it will be inclined to wander because you're leading it a given direction. Also, when it's time to tap the hole you're going to need, you can tap it in the same setup, using the spindle to follow the tap. That way you get a nice, in-line tapped hole. You following me here?

What you and I need to do is to have that fine wife of yours understand that you need a lathe. That would help you with this project, and get you hooked, just like the rest of the poor saps on this forum (did I say that?). After all, when a man owns a few 60° center drills, it's pretty hard to justify unless you have one.

Harold

[steamin10]

Just a note: When machining model RR wheels, the biggest problem I have is the cast iron blanks are notorious for snapping the small center piece off, and sticking it in the blank. Is this because I am hoggy, misaligned or angled tail stock, or just grabby in the cast. I reeaally would like to get better at this, it is such a pain to get the nub out of the hole. Presently, I redrill from the oposite side, and change drills to a squawker, just before I break into the nub and push it out. I dont have a better way. Otherwise, it changes little in drilling bigger and then finish boring the hole to size.

[Harold_V]

Just a note: When machining model RR wheels, the biggest problem I have is the cast iron blanks are notorious for snapping the small center piece off, and sticking it in the blank. Is this because I am hoggy, misaligned or angled tail stock, or just grabby in the cast.

I expect that being grabby in cast iron isn't the cause. It's easy to machine unless it's chilled, and clears chips readily, assuming you allow the center drill the opportunity.
The tip is often broken when starting the hole. Careful observation would be very revealing of the cause. When a center drill is applied with a lathe, it's common for the centerline of the spindle to not be in a common plane with the tailstock. That results in the center drill trying to inscribe a circle. A robust center drill can withstand the thrust and will be self centering. You can actually see it move to center if you pay attention. Not so with a small one, which breaks instead. That's why I recommend they be held lightly, and by a short amount, so they are easily centered, which they do by themselves, given the opportunity. (I don't use a chuck key in this case---just hand tighten the chuck).

If yours are breaking in the cut, with the tip well in the part, the only thing that comes to mind is that chips are packing in the flutes, which are straight, and do not encourage evacuation. I'd suggest you clear the center drill regularly, and feed lightly, so they don't pack tight. Take it slow and easy---even if you can run the spindle reasonably fast. Remember, the surface speed for such a small cutting tool borders on zero, even when running at 1,000 rpm (just 32 sfps). That's at the periphery of the center drill, so the tip is far slower. Cast iron can tolerate at least 100 sfpm, so you're most likely running well under acceptable speed. As a last resort, it might pay to use a little sulfur based cutting oil, in spite of the idea that cast iron can be machined dry.

Harold

[Jackotrades05]

Here is a pix I took last week ,it is not clear as it was not focused correctly.
The next picture I post on her will be of suitable quality!



You will notice that I have a 2-1/2" vise attached to the bed plate , and 3 7/16" bolts locking it in place , so it's pretty darn tight , and plumbed , and zero leveled , ALL ADJ. 3 TIMES ,to be sure.

I also appreciate the time , and thought you guys have taken to help me , even on such a small item as this to be critical to a positive point ,I have rarely found this in these times, again Many Thanks from a Newbie.

Sincerely,Jimmy

[Jackotrades05]

"What you and I need to do is to have that fine wife of yours understand that you need a lathe. That would help you with this project, and get you hooked, just like the rest of the poor saps on this forum (did I say that?). After all, when a man owns a few 60° center drills, it's pretty hard to justify unless you have one.

Harold[/quote] She read Your comment , and replied to Me ,You should get a bigger one than this ., or if I was just pipe dreaming a passing fad to keep designing things like the ONE BELOW


She Said Money is not the problem, it's stupid to get involved with something that you are not willing to Teach others ,GRANDSON !!!! so Thanks again Harold , Just which do You recommend ?

Jimmy, The Gran pop pop x 3 boys