Machining
 

If anyone has any machining questions, they can ask me. I'm a tool and die maker and that's what I do for a living. I'll do my best to help you or at least lead you in the right direction.:D

Hey, sounds great!

#1: How can I get my hands on a milling machine?

Or, if #1 isn't possible,

#2: What can I make from a drill press, bench saw, jigsaw, cordless drill, and a table grinder?

I know that's not quite what you meant, but still :)

I will seriously keep this in mind though.

-Gui

Roger that:D

*and a lathe too!!!

If you guys really want one check our your local auctions. When businesses shut down their stuff can go cheep. I've seen lathes and mills go for a few thousand. :)

But if you want tools auction are great too! I have picked up micrometers for as little as $10 bucks a piece. They have all sorts of things from mics to metal. A lot of tool makers and machinist are up there in age and once they pass on their wives don't want the stuff. I know it sounds morbed but I think they would like to see their stuff put to good use, and trust me they collect everything!!! And let's face it their junk is our robot!

Oh yeah I have seen people turn drill presses into mills but I wouldn't recomend it. Endmills and drill chucks don't mix very well.

A man of true wisdom....

Team 538 got lucky this year. A guy donated a mill and lathe to us. The only down side was, they were recovered from an explosion. Took many weeks, but we scraped black, and sanded rust, rewired motor's, and got them painted. They look really good, and we dont have more than $1000 into them, so we got off good (considering the price of a working mill and lathe).

We have in our primary meeting/work area a Sherline CNC mill and a CNC lathe.

Total cost was about $2000.00, plus tooling, most of which we fabricated.

The machine is low powered enough so that a mistake wouldn't be fatal or apendage-removing, but still decent enough for chunking out parts. We home-brewed the CNC control setup to save money, it costed maybe $200.00 for the controller and power supply, old computer and shareware CNC software. Currently we write all our CNC code BY HAND, but when you have lots of parts to make, it's worth it.

Milling Aluminum
 

I have access to a CNC mill at a University, but have not found anyone who really knows much about machining or selecting tools for it.

I would like to mill a series of triangles into 2024-T3 aluminum, 1/4 inch thick. Cut all the way through.

What cutting tool do I buy to make cuts like this. I would guess something like a 1/4" diameter, double ended 4 flute mill. Is there any rule of thumb or common sizes that tend to be more economical, or work better?

The diameter of the mill will affect inside radius at the corners, of course. A larger mill cutter might be stronger, but would have to remove more material. A smaller cutter would remove less material, but at some point becomes fragile.

And of course, there are differnt coatings on the cutters. What would be an appropriate cutter for aluminum?

Finally, what type of surface speed should you start with?

Regards-
Norm

2 flutes for aluminum and non-ferrous material , 4 for ferrous. You can get by with a 3 flute, but in general they are more expensive. Make sure the bit is capable of center cutting! I can't emphasize that enough. My chassis team leader last year took a non-center cutting bit and tried to route out the pocket required for butt joints in 80/20 - and ruined EVERY piece of our chassis.

If you're doing multiple passes, that end mill geometry selection is okay. cutting all the way thru, 1/4" x 1/4", is a bit aggressive.

3/8" shank bits, between 1/8" to 3/8" in my experience tends to be more economical. My team mostly uses valuebrand HSS bits, with solid carbide bits reserved for special applications. The bits are uncoated. This is due to budget restrictions. TiN is a good choice for most tooling application because of it's lubricating properties on the cut. TiAlN and TiCN are better for high speed commercial operations (10k RPM or above on machining centers) but most people are not equipped to run at these speeds (flood coolant is mandatory).

For coolant we use NewLube, which is a vegetable oil based lubricant. I don't want my kids to have to deal with petroleum distillates.

Make sure that you climb cut your alumninum for a better finish. Off the top of my head, aluminum should be cut at 600 to 800 S.F.P.M. Do the calculation for RPM translation for a 1/4" cutter. (Roughly 3000 RPM is my off-top-off-my-head number).

Lemme know if this helps

-=- Terence

When cutting Al I find that using a cutting fluid called tap magic for Al works great. It stinks a little but it keeps your endmills and drill bits from getting gumed up. If you don't have any or can't get any you can mix a LITTLE kerosen with a standard oil. If you want more info on cutting oils look at the Machinery Handbook.

The Tap Magic makes one able to use four flute end mills for Al as well. You don't have to have center cutting end mills if you predrill first for the center. If you are milling a pocket you can put slight pressure on the milling handle as you crank the table back and fort.

When climb milling be really carful you can break endmills if the table gets away from you. I prefer to leave about .005" for a finish pass and use more cutting fluid on the last pass. It usually gives me a great finish.

Also if you machine any brass or copper dull your drill first. Just take a stone or a file and nock of the cutting edge. This helps keep the drill from grabbing and pulling the work piece out of the vice.

Are there any books about milling and machining especially lathes that you could reccomend? We cleaned out the old tool closet today and found 3 CNC mills very old (one stored it's programs on a microcassete) but operational and they have manual control! they seem similar to the sherline lathes we also got a small 2D mill also but I dont know if it works.
-Andy

I can't think of any names off hand but I do know they make some. I have one from a class I had to take a class when I was an apprentice. I'll find the name out for you but I think you could go to any library and find some.

Is there anything specific you would like to know. Speed and feeds, cutters, coolant, order of turning. You can just ask and I"m sure if I can't answer someone can.

Well, it depends. For small desktop machines, I have a copy of Joe Martin's "Table Top Machining", ISBN 0-9665433-0-0 as well as Doug Briney's "The Home Machinist's Handbook, ISBN 0-8306-1573-3. Both are pretty decent, the latter is what I trained my high school student machine shop leaders on. NEITHER is adequate substitution for actual machining time, standing on the shop and watching the chips curl off.

There are a few very helpful discussion groups on yahoo. groups.yahoo.com, the groups sherline and taigtools seems to have pretty decent advice going. There's also rec.crafts.metalworking, accessable via the google groups feature.

Hope this helps!

-=- Terence

Is there any way to make shaft keyways without a milling machine?

Also, how do keyway broach sets work? Do they go in a some sort of power tool?:confused:

Team 343 is extremely fortunate to be situated in the Hamilton Career Center, where they teach machining, carpentry, auto body, welding, robotics, graphics design, autocad and drafting, video production and editing, and even culinary arts. We have EVERYTHING in house to design, build, machine, weld, paint, and feed the team...

It really depends on the size but most standard key widths you can just order key stock for and sand or grind them to fit if they come a little over size. You should be able to find them from any manufacture.

http://www.mscdirect.com/IWCatSectio...e startFlow=t

that shoud take you to the key stock page from the MSC big book.

If you have a basic broach set you will need an arbor press. All you do is drill your hole for the shaft. Then you place the colar in the hole and the broach in the slot in the colar. You then put it in an arbor press and slowly push it thru. Use lots of oil. Then after the first pass you should have a shim. Place the shim in the slot and broach thru again. I hope that helps. If not let me know and maybe I can find a resource for you.

Aha, I understand how the broach set works now. We need one pronto.

What about keyways in the shaft. Does that require milling? Is there a work-around?

A milling machine would be the easiest way to cut it. Broaching can be dangerous in some ways, but for quickness and for a lot less money, a milling machine will do the same thing. Just make sure where ever you cut the key way is well supported in a vise.

I didn't know how important such equipment would be... :D oh well.. we do have a lathe and mill in my basement.

O yes, with a miller and a lathe, the possibilities are endless.

There are other ways beside a key. It all depends on what you are driving. The easiest way is to use a set screw (I know other teams don't like this) but you can keep them from backing out one of two ways. First the have Nylock set screws that have a nylon insert in the treads. Second they make a thinner set screw call a die set screw. It is used to jam against the first one. They use this in stamping dies to keep the set screws from backing out and at 400 strokes a min they hold just fine. Make sure you put a flat on the shaft or you could have a heck of time getting the part off the shaft.

Another way is something called a taper pin. You have to buy a special reamer to do this but they work well. It's basically a pin that has a taper and you ream a hole to fit. You hammer the taper pin in and it holds really well. If you have ever had to take one out you'll know how well they work. If you have used a lathe the tall stocks use a taper to hold the drill chucks or centers in them.

you can make a clamping collar. You could put a flat on the shaft and make a two half collar that would clamp over it.


Those are some ideas I have done in the past and all do work. I have use them on machines I have built and rebuilt. Some of the Machines have been using those designs for 20 years.

As for putting a keyway in a shaft. The only safe and good way is with a mill. Just make sure you are on center or it won't go together with the part you broached.

I hope this helped. If you have any question or need anything cleared up please just ask.