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View Full Version : best end mill for slotting in 18 gauge galvanized steel 2, 3, or 4 flute?



jimmy482
08-08-2011, 12:06 PM
Here's what I'm trying to slot. http://www.homedepot.com/h_d1/N-5yc1v/R-100374944/h_d2/ProductDisplay?selectedCatgry=SEARCH+ALL&jspStoreDir=hdus&catalogId=10053&navFlow=3&keyword=a23+angle&Ntpc=1&langId=-1&Nu=P_PARENT_ID&storeId=10051&Ntpr=1&ddkey=Search It comes with some 11/64" holes drilled in it. I want to extend those holes to about a 1/2 inch slot with a 11/64" ball nose end mill.

I know that its preferred to use cobalt end mills on steel but would carbide work fine on 18 gauge galvanized steel? Should I choose 2, 3, or 4 flutes?

DFMiller
08-08-2011, 12:16 PM
Are you going to use a Vertical Mill?
What RPM range do you have available.?
Why are you wanting to use a Ball end mill.
HSS should work fine at suitable RPM and feed.
The galvanized stuff is not that healthy if I recall to machine.

Dave

JoeFin
08-08-2011, 12:32 PM
4 flutes - strong tie clamped over a piece of wood to prevent it from flexing too much, extend the endmill .100" past the metal, and if you have it flood coolant to extend you tool life. Biggest problems being the vibration and flex when you are plunging through the metal. After that it should be easy cutting.

I just finished slotting a bunch of 16 ga stainless steel in the cnc

jimmy482
08-08-2011, 12:41 PM
Are you going to use a Vertical Mill?
What RPM range do you have available.?
Why are you wanting to use a Ball end mill.
HSS should work fine at suitable RPM and feed.
The galvanized stuff is not that healthy if I recall to machine.

Dave

I don't have a mill. I was going to try to extend the holes into slots with an electric hand drill with the a23 angle held firmly in place with a strong clamp. Yes I know that's not the preferred method for slotting with end mills, but I don't have a mill. Would the 11/64" square end end mill fit fine into the 11/64" holes? That's the reason I wanted ball end, cause i wasn't sure if the square end would fit into a round hole. Even if it didn't I guess it wouldn't matter if the end mill is center cutting. Does square end have any advantages over ball end?

My electric drill has a rpm range of 0-2250 rpm. So I should go with HSS 11/64" square end end mill? Should I choose 2, 3, or 4 flutes, and what coating should I choose?

tdmidget
08-08-2011, 12:49 PM
tin snips and a file

Tony
08-08-2011, 12:56 PM
hand drill is going to be dangerous and give you bad results.
How many of these do you have to do?

Open up the first hole to 1/2", drill a second hole as close as you can and
use a file.

18 gauge isn't so bad, put it in a good vice, a file will cut it quickly.
And no fumes!

I bet you could get a sheetmetal nibbler from HF for less than the cost of
a good endmill.

jimmy482
08-08-2011, 01:14 PM
hand drill is going to be dangerous and give you bad results.
How many of these do you have to do?

Open up the first hole to 1/2", drill a second hole as close as you can and
use a file.

18 gauge isn't so bad, put it in a good vice, a file will cut it quickly.
And no fumes!

I bet you could get a sheetmetal nibbler from HF for less than the cost of
a good endmill.

I have about 16 A23 angles i have to do. I'm trying to slot 3 holes on each one. Should I get this nibbler? http://www.harborfreight.com/16-gauge-air-nibbler-96661.html

Willy
08-08-2011, 01:18 PM
Do the slots have to be precise? Not that they would be with a hand held drill.
Why not use a small zip wheel using a die grinder or even a Dremel.

jimmy482
08-08-2011, 01:25 PM
Do the slots have to be precise? Not that they would be with a hand held drill.
Why not use a small zip wheel using a die grinder or even a Dremel.

No the slots don't have to be perfect.

jimmy482
08-08-2011, 01:32 PM
Should I just drill a 11/64" hole as close as possible to the hole then grind off whats left in between with a grinder?

lakeside53
08-08-2011, 01:38 PM
No the slots don't have to be perfect.

..Then you aren't going to be using a hand-held endmill (bad idea) in anycase.

If you need perfection, send them out or find someone with a mill.

Toolguy
08-08-2011, 01:42 PM
Should I just drill a 11/64" hole as close as possible to the hole then grind off whats left in between with a grinder?

Yes. That would be the easiest way to go.

DFMiller
08-08-2011, 02:14 PM
I think a Dremel or other hand held grinder or drill and file is the best method.
I would not use a had drill and a end mill. !
Material like that even difficult with a mill. Holding the material is difficult. Best results are as stated earlier is a block of wood and some clamps.


A rat tail file is how I would probably do it with the equipment at hand. Would probably drill a hole at both ends of slot. A small handheld nibbler would also most likely work.

Dave

Willy
08-08-2011, 02:17 PM
By the way Jimmy, welcome to the circus.:)

Stick around, I think you'll like it here.

Arcane
08-08-2011, 02:33 PM
Chain saw files (used for sharpening the cutting chain) come in various different sizes including 11/64 and are quite cheap. These have parallel sides unlike a rat tail file which has tapered sides. I'd drill the end of the slot with an 11/64 drill bit and then use an 11/64 chainsaw file with a bit of elbow grease to make the slot. Mark out the center of the new hole and use a prick punch to give yourself a divot to center the drill bit in..helps immensely to prevent it from walking. Use a good quality sharp drill bit too.

jimmy482
10-18-2011, 02:23 AM
Would I be able to use this air nibbler to make 1/4 inch slots if I drilled a 1/4 inch hole in the A23 angle bracket, and then put the angle bracket in a clamp on vise? http://www.youtube.com/watch?v=Pv0WOQEbK_M http://www.youtube.com/watch?v=HZbBwJm7Ew8

Evan
10-18-2011, 02:47 AM
As has already been suggested, trying to control an end mill in a hand drill is a bad idea.

The air nibbler may work depending on the real rating in steel. You may find it difficult to control.

A hand nibbler will work. I have one that I have used for about 30+ years. They are available from most electronics dealers and look like this:

http://ixian.ca/pics9/nibbler.jpg

I would be tempted to try the air nibbler as it isn't much more expensive than a hand nibbler. That always makes me a bit suspicious though.

note: It doesn't look like the air nibbler will fit through a 1/4" hole.

Boostinjdm
10-18-2011, 02:57 AM
Die grinder and a 1/4" bur...

jimmy482
10-18-2011, 03:08 AM
As has already been suggested, trying to control an end mill in a hand drill is a bad idea.

The air nibbler may work depending on the real rating in steel. You may find it difficult to control.

A hand nibbler will work. I have one that I have used for about 30+ years. They are available from most electronics dealers and look like this:

http://ixian.ca/pics9/nibbler.jpg

I would be tempted to try the air nibbler as it isn't much more expensive than a hand nibbler. That always makes me a bit suspicious though.

note: It doesn't look like the air nibbler will fit through a 1/4" hole.

Yeah, I was wrong. It nibbles off a 1/4 inch, but idk how big of hole it would need to fit through. Maybe I could still use the air nibbler to make a 1/4 inch slot, but it would need to drill a bigger hole to insert the air nibbler. Would a hand nibbler be able to slot 18 gauge zinc galvanized steel?

darryl
10-18-2011, 03:23 AM
It's too bad you can't buy a 'file blade' that would fit a jigsaw. It would make that job easier if you could mount a round file that fits the hole. I've never seen one though.

That could be a job for a makeshift broach. Find a metal-cutting reciprocating saw blade that's about as thick as the diameter of those holes. Grind the back edge of it into a slight taper, with the small end being just small enough to enter the hole and extend through it a bit. You may have to cut the blade shorter so it won't simply bend when you smash it with a hammer. You would make a 'bottom die', which would be two pieces of sturdy metal spaced apart by the width of the hole. Enter the modified saw blade, fit it into the slot in the bottom die, align the part to suit, whack with hammer. The hole will be extended to one side as the taper advances the blade forward.

You can see that a suitable back-up anvil or something would be required, and some forms of support to keep things lined up.

Boostinjdm
10-18-2011, 04:24 AM
It's too bad you can't buy a 'file blade' that would fit a jigsaw.

You can get 'em for a recip saw.

Evan
10-18-2011, 08:36 AM
The Adel hand nibbler I have will easily slot 18 gauge but it was made back when the US still had smokestacks. You can still buy the same tool amazingly enough and it is apparently still made in the USA from USA material. The advertised capacity is 18 gauge steel and that is conservative.

http://www.adelnibbler.com/How_to_use_Adel_nibbling.htm

However, it costs $35.00.

Ron of Va
10-18-2011, 10:11 AM
For sheet metal: Anvil + Cold Chisel + Hammer = square hole

jimmy482
10-18-2011, 02:34 PM
The Adel hand nibbler I have will easily slot 18 gauge but it was made back when the US still had smokestacks. You can still buy the same tool amazingly enough and it is apparently still made in the USA from USA material. The advertised capacity is 18 gauge steel and that is conservative.

http://www.adelnibbler.com/How_to_use_Adel_nibbling.htm

However, it costs $35.00.
Would it work on 18 gauge galvanized steel? Some other hand nibblers I was looking at said they could only handle up to 18 gauge soft steel. Is it adjustable in the size of the slugs of metal it nibbles out?

Evan
10-18-2011, 05:23 PM
Galvanized should make no difference. The tool is not adjustable except by how you position it for the next bite.

jimmy482
10-18-2011, 07:03 PM
Galvanized should make no difference. The tool is not adjustable except by how you position it for the next bite.

So it nibbles slugs out at about a 1/4"? I'll probably get a new one, but what do you think the condition of this adel nibbler looks like? http://www.ebay.com/itm/ADEL-NIBBLER-ORIGINAL-VERSION-WORKS-WELL-/370515597153 After inserting the nibbler into a 7/16" hole how long do you think it would take to make a half inch slot?

What do you think of the klein nibbler? http://www.amazon.com/Klein-Tools-76011B-Nibbler-Tool/dp/B0000CBJCT Is it as a good as a adel nibbler?

Evan
10-18-2011, 10:02 PM
It isn't possible to judge the condition by photos. The actual shear edge is what matters. I am not familiar with the Klein nibbler so I cannot comment on it.

A nibbler is a slow way to make a slot but it beats chain drilling and filing it out. You will still need to touch up the edges with a file after nibbling the slot.

jimmy482
10-19-2011, 01:00 AM
It isn't possible to judge the condition by photos. The actual shear edge is what matters. I am not familiar with the Klein nibbler so I cannot comment on it.

A nibbler is a slow way to make a slot but it beats chain drilling and filing it out. You will still need to touch up the edges with a file after nibbling the slot.

Evan do you think a sheet metal hole punch kit like this one could get the job done? http://www.amazon.com/Neiko-Power-Punch-Sheet-Metal/dp/B0002T87CW/ref=pd_bxgy_hi_text_c/177-8416266-8130657

darryl
10-19-2011, 02:08 AM
'a nibbler is a slow way to make a slot' I dunno about that. It might take out only a small chunk of material per nibble, but you could be done before you had any other setup put together to do the job. My only problem with a hand nibbler is that you can easily fit it onto stuff that it isn't capable of nibbling- then you break it. By the way, galvanized is no tougher to nibble than any other steel sheet, but stainless takes a bit more force.

With the right punch setup, various openings would be quick to do- round holes, square holes, slots, etc. Of course you need the suitable punches and dies, and by the time you've purchased the setup you're many dollars down. I've just about finished making a punch that will make 1/4 inch square holes- and that's it. If I want a slot I punch and move, punch again, etc. Going with 1/4 inch square was about my best compromise- not too big that it takes more than hand power, and not so small that you'd have to punch away for hours just to get somewhere.

I don't know if my camera is working- in fact I don't know where it is actually. But a brief description- the punch is a hss lathe cutting bit, 2 inches long and 1/4 inch square. For the die I used a socket from a 1/4 inch socket set. I picked the smallest one that had a full size hole through it so the divets could fall through. I had to grind a fair amount of steel off the end of it so the square hole edges became flush with the end. Two other sockets were used as guides for the cutting bit. I also used some brass shim to minimize play and keep the cutting tool well centered in the guide sockets. The body of the machine is carved out of a piece of 2 x 4 inch x 1/4 wall steel tubing. Once the mechanism was all together, the bottom die was positioned and epoxied into place. I tried to 'hollow grind' the end of the lathe bit to minimize the force it takes to punch through sheet material. My first job was in .045 stainless sheet, which it handles fairly easily. If I can post some pictures I'll elaborate a bit more.

Suffice to say, it's now fast and easy for me to make a small square hole in sheet material. That's the start- if I want a slot I just move the sheet along and punch again, then again, etc. The thing is bolted to the workbench and anchored to the wall, so I can just grab the handle and yank. I didn't have to buy any materials or punch and die parts, so that worked out too- Sacrificing the 1/4 inch drive sockets was no loss either since I have tons of them that I never use.

darryl
10-19-2011, 03:33 AM
Just a little drawing of my punch design, side view.

http://img.photobucket.com/albums/v136/heinrich/punch.jpg

The handle is a piece of 1 inch sq tubing. Between the handle and the toolbit is a push rod. The top of the toolbit is rounded over, and the pushrod centers on that. At the upper end of the pushrod, it is splayed open a bit so it can center itself under the handle. Pulling the handle forward pushes the rod downwards. Not shown for clarity purposes is a pair of springs which pulls up on the toolbit and keeps all these parts together. Between the length of the handle and the distance between the pivot bolt and the top of the pushrod, I get about a 20 to 1 advantage. Moving the handle 5 inches gives me a stroke of about 1/4 inch on the toolbit. I used a 3/8 grade 8 bolt as the pivot.

Evan
10-19-2011, 05:40 PM
Sorry to be so slow answering but I have other things going on right now that are taking up my time. A bench punch of some sort would be optimum for that kind of job. It certainly isn't beyond reason to make one even without a milling machine. Best proof of that is that I built my milling machine almost entirely using my lathe. One thing to remember about a lathe is that a flat surface is also a surface of revolution. That being so, a lathe is capable of making any plane faced solid that will fit within it work envelope. That includes perfect cubes, rectangular punches and even rectangular dies.