Hole cutting

[oczad]

can anyone offer a better solution to hole saws to cut tube socket holes in aluminum? I used hole saws in the last chassis and it was a PITA and the holes weren't very clean or accurate. Is there anything cheap short of buying a drill press or getting a machine shop to do it? (last MS i asked wanted $50 for 6 socket holes !)

[sluckey]

unibit or step bit

[mister ed]

I use a Greenlee chassis punch on octals, and I use a step drill on smaller holes, ( although I would use a chassis punch on ALL tube socket holes, if the Greenlees' weren't so expensive).

[Iannone]

I use a hole punch.  Antique Electronics sells them and they are easy to use.

[panhead]

From Ocean State Electronics
http://www.oselectronics.com/ose_p64.htm

5 Piece Chassis Punch Set

"Why spend $60 for 1 chassis punch when you can have a set of 5 for the same amount. Don't be fooled by the low price. One of  our best selling items. Hundreds sold to satisfied customers. Complete set of punches in a leatherette carrying case. All  precision machined of top grade steel.

Includes the following  sizes: 5/8", 11/16", 3/4", 1", & 1-3/16". Also included is a burring reamer."   

   110E..........................$59.95
 QTY:       

 

[mister ed]

YES !!! For Godsakes don't be FOOLED !!!!! 

From Ocean State Electronics
http://www.oselectronics.com/ose_p64.htm

5 Piece Chassis Punch Set

"Why spend $60 for 1 chassis punch when you can have a set of 5 for the same amount. Don't be fooled by the low price. One of  our best selling items. Hundreds sold to satisfied customers. Complete set of punches in a leatherette carrying case. All  precision machined of top grade steel.

Includes the following  sizes: 5/8", 11/16", 3/4", 1", & 1-3/16". Also included is a burring reamer."  

   110E..........................$59.95
 QTY:       

 

YES!!!! For Chrissakes DON'T BE FOOLED !!!!!

[panhead]

I have the Ocean State Electronics puch set and it's great. Just drill a 3/8 dia. hole and use the punch with a big wrench for thick stuff. The T-handle works fine for aluminum.

[oczad]

Thats what i thought.....nothing cheap, tho the step bits aren't too bad. Thing is, theres a good chance, in fact it's almost a sure thing that the amp i'm about to receive parts for will be my last. So i hate to spend more on the bit then the chassis i'll be using it on. Since i may never need it again. I may have to just go with the hole saws i already have. thanks tho.

[mick]

Just put a drop of oil on the threads before you punch out the chassis.   I have just also learned to put a block of wood on the other side of what I am drilling through.   Drill right through the chassis into the block.   Makes for a better looking hole.   

[tubesornothing]

Unibit - fast, easy, needs a little clean up
Hole punch - takes a minute or two longer, but makes a real nice hole - mouser has some cheaper deltron units that work well

TON

[Blind Lemon]

Last build, yea right and pigs fly. Who you kidd'in. 3 amps ago was my last one......or was that 4 amps ago. ;D

[billcreller]

  Harbor Freight has the step drills. Get the set of two with the big one in it. I use the big one for octals.
They are much less expensive than the trade-named "Unibit"  (of course!! they are made in China!!)

[PRNDL]

One option would be to drill holes with the largest bit you have and then use a Dremel grinder bit (on the drill) to enlarge it. Those bits are about $5 each and should work well with soft aluminum.


OTOH a chassis punch set is a wise investment that makes everything much easier.

[oczad]

Harbor Freight has the step drills

Harbor freight !!! God, i forgot about that place. They have all kinds of stuff like this cheap. I'm heading there this weekend. Good call.

One option would be to drill holes with the largest bit you have and then use a Dremel grinder bit (on the drill) to enlarge it. Those bits are about $5 each and should work well with soft aluminum.

actually with aluminum those grinder bits load up and stop working real fast. Plus i've use those before and in fact used them AFTER i cut the holes with a hole saw last time to smooth out the edges. Better than nothing, but still not very clean and accurate.

[LooseChange]

Question about the step drill.  I use it all the time but it always leaves a large burr.  At times it's very hard to get at to de-burr.  (Most chassis I drill are steel).  Is there a trick to using these things?

I use punches too.

[Dynaflow]

 I don't think so, when the last bit of material gets real thin it yields to the downward pressure and just folds out causing that bur. Holesaws do it to, twist drills leave a rounded triangular bur. Grinding off the bur I think is gonna be required with anything but punching them or lasering them. :D

Regards,

Dyna

[mick]

when the last bit of material gets real thin it yields to the downward pressure and just folds out causing that bur.

Yup,   thats what happens.   Which is why I started to not use a unibit and put a block of wood behind the chassis,  I then drill right into the wood.   Holes actually look pretty good with little or no burr.

[bluesbear]

I use step drill bits, a Unibit for the 9 pins and a Greenlee for the octals. Then, I use a dremel to deburr. The 2 bits cost under $60 and seem like they'll outlive me. I tried one of those cheap hole punches. I did one hole. It worked but it took less time to do every other hole in the chassis using step bits.
Dave

[HCS]

Go to Harbour Freight and pick up the punch set for for $15.99 and the step drill set(3 drill) for $12.  For $30 you have everything you need.  I have used their step drills for 3 years and they still aren't dull. 
Here is the HF punch set:

[sluckey]

Question about the step drill.  I use it all the time but it always leaves a large burr.

Just flip the chassis over and run the drill thru again. Use light pressure and let the next size step deburr. Be careful. You don't want to drill all the way thru, just deburr. This works best in a drill press. If doing aluminum you can just turn the chuck by hand to deburr.

[Platefire]

Wow! You mean they have a step drill large enough to do Octals, I haven't seen one. I have the smaller one for year for up to about 7/8" I think and it still works good.

[sluckey]

Lowes has an Irwin 7/8" to 1-1/8" and a big Greenlee step bit. The Greenlee is usually on the electrical aisle.

[tubesornothing]

Question about the step drill.  I use it all the time but it always leaves a large burr.  At times it's very hard to get at to de-burr.  (Most chassis I drill are steel).  Is there a trick to using these things?

There is also a deburr tool you can get...  http://www.kbctools.com/can/main.cfm  go to page 566

[oczad]

Go to Harbour Freight and pick up the punch set for for $15.99 and the step drill set(3 drill) for $12.  For $30 you have everything you need.  I have used their step drills for 3 years and they still aren't dull.
Here is the HF punch set:

Why both? Can't just do it with the punch set?

[bluesbear]

"The Greenlee is usually on the electrical aisle."

That's where I found it at Lowes. There's a + or - 6' section with just electrical tools in one of the electrical aisles.

"Why both? Can't just do it with the punch set?"

You could and many do. If you don't have a drill press, the punch set is probably better, particularly for the octal. It's fairly hard to control with the larger bit although I do it when I'm in a hurry. Personally, I find it about 10 times faster to use the step bits.... but I have a drill press. A little cheesey one would do. I use it for a lot more than punching holes in chassis. Second to the table saw, it's the most useful shop tool I own (I'm not counting the portable drill here; I use it every day even without amp work).
Dave

[oczad]

funny story...i ended up getting the 2 pack of step bits billcreller recommended at HF this morning.  I had the punch set in my hand and had planned on getting that. then i was looking at the step bits but figured the punches were the better solution. While i was looking a japanese guy came over and said to me "they good". he barely spoke english but he kept trying to convince me. Then he offered to show me something in his truck. i couldn't quite understand him but i assumed he meant he wanted to show me a hole he made in something with the step bits. instead he brings me to his truck which was obviously his work truck full of tools and construction supplies. he then pulled out a drill and the step bit and started drilling thru various pieces of metal he had in his truck ! Talk about a recommendation ! I was howling inside. I could never tell exactly what the words were he was speaking, but in many instances i got the gist of what he was saying and he had kept telling me they were very good, and there was no mistaking his enthusiasm about the product. After that demo i was convinced ! LOL! anyways, that and the fact that the bits would allow me to drill every single hole in my chassis made me realize these things are truly the only way to go. I can use my power driver with a small hex bit to start all the holes accuratly then ream them to size with the step bit. My only worry is the drill taking control away from me and going a step too far on some of the holes. But i think it'll be ok. As for burrs, thats no problem. I can dremel the edges quickly to smooth them.

Anyways, i thought that was a rather amusing story that i had to post here. By the way, the punch set looked great too, but considering the ease of the step bit and the fact i can use it for tiny holes all the way up to 1-3/8 holes without changing bits, it was a no brainer. Plus if i never build another amp they will still come in handy for many other drilling uses.

[RicharD]

A unibit is pretty much a standard issue tool for an electrician.  As with most drill bits, the tip is the first thang to go.  I highly recommend drilling a pilot hole first.  This will prolong the life of the bit and increase accuracy.  It's always a good practice to lock and block your work, especially when drilling stainless.  I had a journeyman slice his hand open drilling a stainless 1 gang plate, and this was after I told him to mount the plate to a piece of wood before drilling it which he didn't do.  Watch your pressure when using a unibit.  Once them thangs get spinning, they like to eat their way through.  I can't tell you how many times I drilled a hole 1 step too big.

-Richard

[jjasilli]

Don't worry about the unibit, it's easy to control.  Accidentally to the next step is not a problem.  For larger holes, like for power tube sockets, it's better to use a drill press, but not necessary.  If you use top mounting tube sockets, minor imperfections will be covered.

If you drill from outside the chassis, you can then use the next step of unibit itself to de-burr on the inside of the chassis. 

[Dynaflow]

 They are pretty easy to control, to me easier than a twist bit by far. Once you get the bit in the project (pilot hole recommended as mentioned) the only real trick is to stop on the step you want, so don't go crazy pushing down on it until you get used to how fast it cuts (which is pretty darn fast). I often will use a sharpie on the step above the one I want to cut with so I know when to stop (being old and having somewhat corrected eyesight is hell).

Regards,

Dyna

[oczad]

Man o man, where have these da*n step bits been all my life ?! I was shocked to find the final shipment that includes the chassis arrive today at noon. I thought it wouldn't be here till mid week. So i had the opportunity to start the build and try the step bits. The large one wasn't great. i don't know why, but it was slow and the holes weren't particularly clean. I guess it's the lesser leverage the bit has being wider.Then again, it was even like that on the smaller parts that were equal to the diameters on the smaller bit. Not to mention the holes tended to wander causing me to have to stop a size smaller on the octal holes so i could use the dremel to work the holes in opposite directions so they'd line up. luckily i was able to get them right. But the smaller bit is a gift from god !  I was able to knock out the controls and all front panel holes in no time nice and accurately. that thing will get plenty of use, and i may have to make it back down the HF again soon before the sale ands on the smaller 3 piece set for 9 bucks. These things are fantastic. wish i'd known about them years ago. I can however now see what someone said about getting both  the step bits and the punches for the octals. Makes perfect sense now. I may have to pick those up too....tho of course, this will definatly be my last amp. :)

Anyways, i took today off to make it a 4 day weekend and now that i have all the parts i'm going to be a very busy boy ! Thanks for the advice guys, you really helped.

[PRR]

On Hammond Aluminum chassis, with a drillpress, and a good supply of oak scraps:

Just use a spade bit. The kind sold cheap for holes in wood. Look for one with lips on the edge, we don't really need to drill the center.

Clamp VERY well. When that large scraping-edge hits a knot in the aluminum (or in the oak backer) it will want to fly.

If done right, the point goes through your mark and pilots in the oak, the lips circle-cut the aluminum, then you see a whirling disk and you are done. If lipless, you'll scrape a lot of aluminum, but it's scrap anyway; just be careful it don't grab.

Yeah, wood bits won't last forever cutting metal, but you can hack a lot of Al with a $3 bit. I think I paid $5 for a name-brand 1.125" to mount my Octal.

You could probably do one or two holes in thin mild steel before a spade bit quit. In thick (Fender gauge) steel, it may not work. Stainless steel is hopeless.

[Greasehorse]

Note on punches...there are chassis punches..size on these is actual OD..and there are knock out punches..size on these is for electrical panel and box knock outs and size is size of knockout, not OD...
A knockout punch may be called a 1/2" but actually be 3/4" OD (outside diameter). They can sometimes be used but you need to measure carefully. Ebay is a good source for Greenley punches and they work well and are fairly fast...just drill a hole for the bolt and screw it down until it cuts a clean hole in the chassis. The one's with the ball bearing on them cut easier. A person can buy one with a ball bearing on it and use the bolt and bearing on the other sizes also...There are many sizes so watch out. The sockets vary in size also.

[DummyLoad]

can anyone offer a better solution to hole saws to cut tube socket holes in aluminum? I used hole saws in the last chassis and it was a PITA and the holes weren't very clean or accurate. Is there anything cheap short of buying a drill press or getting a machine shop to do it? (last MS i asked wanted $50 for 6 socket holes !)

to make a decent hole, if you are using any type of drill/mill process, you MUST secure the work. a drill press would be the best bet, a milling machine better still, or optimally a CNC machine. $50.00 for 6 holes is a fair price if you want precision work.

as other have mentioned, punches work very well. use a good quality hardened punch such as greenlee. the harbor freight stuff works, but is of inferior quality.

[YD]

Go to Harbour Freight and pick up the punch set for for $15.99 and the step drill set(3 drill) for $12.  For $30 you have everything you need.  I have used their step drills for 3 years and they still aren't dull. 
Here is the HF punch set:

I've caught a sale at the local store a few times $9.99 for the punch set- at that price I can afford to not buy Greenleys and if these do break oh well :)   For the amount of holes I punch, it's a great deal.

[Greasehorse]

Note: The Harbor Freight punch set for electrical panel knockouts. The "sizes" listed are not real sizes but electrician "sizes" or pipe sizes. Small pipes are sized by ID - not OD as radio chassis punches are sized!
From HF website:
Includes punches and dies for 1/2", 3/4", 1" and 1-1/4" pipe and conduit, in a blow mold case

Of course, by measuring them I am sure some might be used for sockets...

[PRR]

> electrical panel knockouts. The "sizes" listed are not real sizes but electrician "sizes" or pipe sizes. Small pipes are sized by ID - not OD...

Not even ID anymore.

Over a century back, strip iron was hammered around rods and beaten together to make gas pipe. The size of this rod was the ID. The iron was poor, so it had to be thick for strength and gas-tight seam. So ID plus iron equals OD. Somehow the industry settled on appropriate thickness and OD.

The outside of the ends were threaded and couplings elbows tees and burners were used to put the job together.

Iron got better and steel better yet. They did not need so much thickness. But they could not change the outside diameter, because the new improved pipe had to fit all the old couplings etc. So the ID got bigger.

That's standard pipe suitable for domestic water supply and steam-heat. High-pressure applications came along, and Extra and Double-Extra pipe was made. The OD stuck with the established sizes, so pipefitters did not need new threading dies. The ID was reduced to gain wall thickness and strength.

Early pipe strength was uncertain. Eventually some Standards were written. Common pipe was assumed to take 40psi nominal (with huge safety margin) and listed on Schedule 40. X and XX strength became Sch 80 and Sch 160.

Some early electric was run in the gas-pipe of the gas-lamps it was replacing. Electrical couplings are gas-pipe couplings, though the thread is straight running instead of the taper thread used to make gas-pipe joints gas-tight.

Electrical does not need any great strength. In high-abuse locations, true pipe may be used; most wiring uses EMT, thin-wall tubing which must be adapted to gaspipe-threaded fittings.

"1/8 inch Trade Size" is 0.4" outside. In Sch 40 (common pipe) it is 0.269" ID.
"1/4 inch Trade Size" is 0.540" outside. In Sch 40 (common pipe) it is 0.364" ID.
"3/8 inch Trade Size" is 0.675" outside. In Sch 40 (common pipe) it is 0.493" ID.
"1/2 inch Trade Size" is 0.840" outside. In Sch 40 (common pipe) it is 0.622" ID.
"3/4 inch Trade Size" is 1.05" outside. In Sch 40 (common pipe) it is 0.824" ID.
"1 inch Trade Size" is 1.315" outside. In Sch 40 (common pipe) it is 1.049" ID.

These are pipe size... electrical work being not gas-tight, the electrician prefers some slack between hole and fitting, and the fitting's shoulders will cover the gap. Electrical knock-outs may be noticeably larger than the above numbers.

You'd think, with all the conduit I've screwed, I'd know how big the holes really are. But I don't, my boxes are buried, and I know there are electricians on this forum who have boxes handy to measure.

[Greasehorse]

Unless it has changed since 88....
Smaller pipe up to 6" ID is called by ID size (1" ID = 1 inch pipe) and the OD is controlled by the schedule #
With exceptions for custom sizes and materials.

Smaller conduit is called by OD IIRC and I have no idea about rigid or large conduit...

Here's a sizing chart for steel pipe...
http://mdmetric.com/tech/pipe0010.htm

[Katie 77]

Just use a spade bit. The kind sold cheap for holes in wood. Look for one with lips on the edge, we don't really need to drill the center.

before I got unitbits, this method worked pretty good...using tap oil to lub it made a really nice hole

fwiw, I use tapping oil on the unibits, too...faster, cleaner hole in Al...cleans up w/ alcohol

[G._Hoffman]

Question about the step drill.  I use it all the time but it always leaves a large burr.

Just flip the chassis over and run the drill thru again. Use light pressure and let the next size step deburr. Be careful. You don't want to drill all the way thru, just deburr. This works best in a drill press. If doing aluminum you can just turn the chuck by hand to deburr.

Or, only run the step bit about 1/2-3/4 of the way through, and then flip and finish the hole from the other side.  Those step bits self center really well, so it works quite well.  Though I've usually done it your way, but I use my method a lot for wood working (a little different - use a brad point until just the center point pokes through, and then use that as a guide from the other side - absolutely no blow out ever, which is a Very Big Deal for peghead overlays).


Gabriel

[Shrapnel]

Sorry I'm resurecting this old thread, but...

I've got some questions here that perhaps someone can help me with.

On the knockout punches, are they pretty much standardized as far as what sized hole is punched say, for the 1/2" pipe?
On the premise that the answer above is yes, what pipe sizes should I look for, for say 9-pin (A_7 types), octals, and 7-pin (AQ5) sockets.

I've also heard that the punches at harbor are not tempered well, and don't temper well. What's the actual experiences with these punches?

The step bits from Harbor, are they pretty decent quality.

Also how many people use punches for the holes for pots, jacks, and switches?

I know Harbor Freight is cheap, chinese made type stuff for the most part, but how to they really stack up on the stuff we'd use them for? Brakes, Step-bits, punches.

EDIT:
NM on the hole sizes... reread the thread.  Probably will stick with step bits unless I find explicit definitions of OD on the punches.

[69SG]

I bought two round trip tickets to Hawaii on Harbor Freight Airlines.
 
I want a refund!

[kagliostro]

If I want to obtain more than a chassis of the same kind (or if I want to have a clean job)

As a guide I use a bar of wood 25 or 30mm thick and a little larger than the chassis that I have to drill, I put around an edge (small slats of wood) and do the chassi fit it exactly

I measure all and make my holes on the wood

then, when I want to drill a chassi I only put it in the wood guide ad fast drill the hole

If I build an exact guide, when I drill holes I have't negative vibrations and the holes are perfect and at their right place in a small time

If I have to use the guide very often I put a small piece of brass pipe (of course I must drill the holes in the wood a little larger, as my hole saw must fit the hole in the brass pipe, not in the wood)

Pay attention that the bar of wood must be more thick than centering the tip protrudes from hole saw

Kagliostro

[Sundhy]

For me, step drills are the way to go.  I use .080 Aluminum for chassis.  I can drill out a complete amp (with center punch patterns) in 1 hr. and 20 minutes.  Yes a little clean up is required.  Don't try this with a hand drill.  The drill press is the only way to go.  Even a small bench drill press would work great.  With 3 different size of step drills and you can drill out 1/4" to 1-1/8".  I drill a smaller pilot hole first.

Sundhy

[Shrapnel]

Go to Harbour Freight and pick up the punch set for for $15.99 [...]  I have used their step drills for 3 years and they still aren't dull.  
Here is the HF punch set:

If the exact same set, it seems to be $25.00 now in my local store. The sizes listed on the punch set, the are pipe sizes? or hole sizes? (Store thought the ones I seen to be hole sizes.) (need 'em for the sockets, probably drill the rest normally.) I'm an apartment dweller right now, so the idea of a drill press isn't really a viable one. I should make note the box I seen did not make note it was pipe size or hole size.

[Frankenamp]

Best thing to do is to go there and put a caliper on the punch and see what it really is. Since it's coming from PRC I would assume that it's gonna be a metric sumpthin or' other... If it's a few thou larger no big whoop, but if it's a bit small then you're back at it with ye old rat-tail file for a few hours.

[69SG]

I built my first three with a Mr Dremel...hahaha.
Have fun!

[Dynaflow]

 Wow, your patient... 

Regards,

Dyna

[tubeswell]

Another vote for punches.

If you can't afford to buy 'em all at once, then get them one at a time

[darkbluemurder]

unibit or step bit

+1. The step bit saves me much time and works really well.

[Rosser]

Anybody have a punch for the strain-relief clip on the power cord? In the past, I just drilled a smaller round hole, then used a rat file/flat file to enlarge the hole and make the flat part of the "D." It was very time consuming, but the only D-shaped punch I've seen was super expensive. Any suggestions?