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billyzelsnack
10-30-2008, 01:59 AM
I'm in the market for a metal brake. Mostly for servo brackets and chassis. Thin aluminum and steel. I understand how a basic brake can make 90 degree bends, but beyond that I am clueless. What features should I even be looking for? My price range would depend on my mood and how useful I can see it being in the future on random tasks. Space is a premium though so I don't want a giant machine taking up half my basement.

Adrenalynn
10-30-2008, 02:28 AM
For bending servo brackets and chassis, you're probably looking for what's known as a "finger brake" aka "pan brake" aka "box brake"

A finger brake has metal fingers of various sizes that can be moved around. So you can make a 90 bend, then put the bend in the empty area and a metal finger over the next bend to make, and create that bend without tweaking or binding what you've already bent.

I suspect a simple 19Gauge 24" finger brake from harbor freight is sufficient for most robot building stuff where brackets or light gauge chassis are concerned. The nice thing about that little brake is that it has fingers all the way down to 1", which is pretty uncommon in the bigger brakes in my experience. My big finger brake had 3" fingers at the smallest, up to 32". The little guy from Harbor Freight goes 1" to 10" fingers.

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=45877

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=45876

I also have the regular harbor freight brake, and you know, it's pretty awesome for simple bends. I'm always impressed with it for a non-hydraulic brake. I've had metal on it that's waaay over capacity, and it never complains other than having bubbled the paint. ;) http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=91012

A radius brake bends metal in rounded (radius) bends. A shear is nice for chopping the metal, so quick and clean for cutting. A bead-roller makes metal beads and corner bends for strength.

So many tools, so little sq-footage. ;) You really just need to figure out first how heavy a gauge you want to be able to work with, and then what _kind_ of bends you want to make, then how large a piece you want to be able to work on. After that - the right tool will just jump right off the page at you. :)

billyzelsnack
10-30-2008, 02:44 AM
Thanks for the break down. I think I definitely will need a one with fingers. Seems like I'd pretty quickly run into a situation where I'd need more than a simple brake can provide. I guess I'll make a trip down to HF and check them out.

gdubb2
10-30-2008, 11:39 AM
For those with a small budget, and little or no room. This break from harbor freight actually works.
http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=39103a

It's small, cheezy,and cheap, but can be modified to do a lot of stuff. I use one for the brackets I've made for Bheka. It bends .050 6061 Al. quite well. One can cut slots in the clamping plate to act as a box break, and use other plate if desired. Mine has slots, bolt holes, and sundry other adaptations.

Gary

Adrenalynn
10-30-2008, 11:57 AM
The 24" box break doesn't take up practically any more footprint - and you don't have to try to modify hardened steel.

Modelmaker
10-30-2008, 12:08 PM
Here's one of the ones I have. For the money it's a very good unit

Amazon.com: Grizzly G0557 24" Box and Pan Brake: Home Improvement

4mem8
10-30-2008, 12:20 PM
M'mmm I'd love one of those, Make my life a lot easier, Don't have those that small in NZ.

Adrenalynn
10-30-2008, 12:51 PM
That looks identical to the Harbor Freight one I linked - but even with shipping for ~$25 less. Good find!

billyzelsnack
10-30-2008, 06:51 PM
I ended up just getting the HF simple $35 one today. Maybe it's a piece of junk. I dunno. Guess I'll find out soon. I've not used it yet, but it seems like I can get most of the value of "fingers" just by using smaller pieces of clamp down stock. I could also not be totally grasping the "fingers" concept either.

Adrenalynn
10-30-2008, 07:32 PM
I think you'll find it's the latter. You'll be needing to drill and tap holes in it, and then machine dies for it - as suggested in the other thread - sorry I can't remember at the moment who suggested it --- Oh, wait, it was ModelMaker, I think. Sorry MM! Blame the prescriptions ;)

srobot
10-30-2008, 08:00 PM
I think you'll find it's the latter. You'll be needing to drill and tap holes in it, and then machine dies for it - as suggested in the other thread - sorry I can't remember at the moment who suggested it --- Oh, wait, it was ModelMaker, I think. Sorry MM! Blame the prescriptions ;)

I'm looking to buy a cheap one also and won't need great quality as long as I can make brackets that work.

billyzelsnack
10-30-2008, 08:16 PM
This is the one I bought..

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=39103

I'm not 100% sure I know how you're supposed to use it. You can't tell from the picture, but really it is just two pieces of metal that are hinged together and a 3rd piece of metal that I guess you clamp on top. It doesn't actually have any clamping mechanism that I can tell and the instructions are pretty much useless.

So.. If the way it works is I use my own clamps to clamp down that 3rd piece of metal, then I should be able to use most any piece of metal and make a finger of most any size. One problem with those fingers on the other machines is that they really are huge relative to the size of the pieces I want to bend. Even 1" is pretty big. Though I also don't really know what I am talking about either.

srobot. I'll try to take a vid when I am making a bracket and I'll put it up on youtube.

As for if I have to put it in the trash.. No worries.. This is Harbor Freight.. They assume everything they sell is trash and will accept pretty much anything for return as long as you return it in time.

Bullit
10-30-2008, 09:58 PM
We bend all our brackets with a brake similar to http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=45877 indicated by Adrenalynn earlier. What you do when you need a smaller finger is just grind one of the small ones down to the size you need. We just use a belt sander. You can usually get spare fingers. We never bend things as wide as 24" anyway so we've never needed extras. It's also important that you use the right kind of materials to bend. If your going to bend aluminum 6061 is tricky and stress fractures easily. It can be bent properly but you have to pay atention to the grain or pre-treat the metal. 6061 is very rigid but we prefer 5052 which is aircraft aluminum. Its a little tougher to cut on the mill but it bends nicely and its extremely tough. Typically I'd say that for humanoid robots 1kg and less 0.040" aluminum is ok, 0.050" is ok up to about 2.5kg then 0.080" is good for robots perhaps up to 6kg. The thicker it is the harder it is to bend. You can get aluminum from many sources but here's one we've found that provides good quality at a good price.
http://www.use-enco.com/CGI/INSRIT?PARTPG=INSRAR2&PMAKA=505-6392&PMPXNO=2866576
for more mateirals just look under raw materials and sheets

Hope this helps.

DresnerRobotics
10-30-2008, 10:31 PM
We bend all our brackets with a brake similar to http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=45877 indicated by Adrenalynn earlier. What you do when you need a smaller finger is just grind one of the small ones down to the size you need. We just use a belt sander. You can usually get spare fingers. We never bend things as wide as 24" anyway so we've never needed extras. It's also important that you use the right kind of materials to bend. If your going to bend aluminum 6061 is tricky and stress fractures easily. It can be bent properly but you have to pay atention to the grain or pre-treat the metal. 6061 is very rigid but we prefer 5052 which is aircraft aluminum. Its a little tougher to cut on the mill but it bends nicely and its extremely tough. Typically I'd say that for humanoid robots 1kg and less 0.040" aluminum is ok, 0.050" is ok up to about 2.5kg then 0.080" is good for robots perhaps up to 6kg. The thicker it is the harder it is to bend. You can get aluminum from many sources but here's one we've found that provides good quality at a good price.
http://www.use-enco.com/CGI/INSRIT?PARTPG=INSRAR2&PMAKA=505-6392&PMPXNO=2866576
for more mateirals just look under raw materials and sheets

Hope this helps.

Unbeatable advice. Listen to this man :)

Adrenalynn
10-30-2008, 10:53 PM
+rep on that one! Thanks, Bullit! Agreed across the board.

Adrenalynn
10-30-2008, 11:18 PM
Scotty -

When people don't understand a word I use, I'm hopeful that they'll get out a dictionary, or at least google it.

From Wikipedia, Article "Die (manufacturing)" : "
A die is a specialized tool (http://en.wikipedia.org/wiki/Tool) used in manufacturing industries (http://en.wikipedia.org/wiki/Manufacturing_industries) to cut, shape and form a wide variety of products and components. Like molds (http://en.wikipedia.org/wiki/Molding_(process)) and templates (http://en.wikipedia.org/wiki/Template), dies are generally customized and uniquely matched to the product they are used to create. Products made with dies range from simple paper clips to complex pieces used in advanced technology."

The "fingers" on a box-brake are technically "dies".

billyzelsnack
10-31-2008, 02:01 AM
Thanks Bullit. The aluminum I bought was just what they had at the local hobby shop. I bought all 3 sizes they had just so I could get a feeling for it. I don't know what the blend is, but the thickest is 0.064. We'll see how easy that works and maybe I'll move up to 0.08 if I'm feeling comfortable.

Bullit
10-31-2008, 06:00 AM
If I had to guess, from the local Hobby shop, because I've been there too, I think you have 6061.
You'll know as soon as you bend it or should I say try to bend it. There are lots of alloys of aluminum but 6061 and 5052 are I think the most common in sheet aluminum. In my experience my local hobby shop only carried a very expensive poor grade of 6061 that was as brittle as it could be. One sure thing, if you're determined to make your own brackets, is that before long you'll be an expert :) Another important tool is to have either a sheer to cut aluminum sheets and/or a scroll saw to cut out your parts. We made a lot of parts just with just a scroll saw and a pan box brake. You can print out your part layout on a piece of paper then spray 3m contact adhesive on it then attach the paper to your aluminum sheet to guide you with the scroll saw. The adhesive come off easily with WD-40. Just spray it on after you've cut and wait 10 minutes. The paper and adhesive peels right off. This is a good place to start if you don't have your own CNC. A decent scroll saw is $200-$300, a cheap pan box brake is $200-$300.

Currently we use a small CNC that is a modified Sherline that uses servo motors instead of steppers from http://www.imsrv.com I think the mill is about $2500 and then you need to add an enclosure and bits etc. It's a decent hobby mill but its not for production. Someday I'd like to have a bigger one :)

Hope this helps.

For details on aluminum alloys a good place to look and find some materials is here
http://www.mcmaster.com
just search for aluminum and then sheet. Mcmaster is full of good information and products. They have high quality sheet aluminum too just a bit more expensive then Enco.

billyzelsnack
10-31-2008, 09:54 PM
Scroll saw? I ask because I had been tempted to get buy a scroll saw, but figured a metal bandsaw would be a better plan if I was to cut metal with it. If a scroll saw works nicely for metal too then that's great.

Bullit
10-31-2008, 10:42 PM
A metal band saw is really for heavier stuff. What you want is a scroll saw and a blade with high number of tpi (teeth per inch) designed for non-ferrous metals. Most large hardware stores carry these. I tried all kinds of fine jewelers blades and found for this type of work the generic blades are tougher where the jewelers blades can do really fine work, they break easily. The other tool thats nice to have for aluminum work is a belt / disc sander but sand paper and a small file works well too.

For small tight bends that don't fit in the brake for one reason or another we use an old planer blade (2"x10"x0.125" tool steel) a vise and a hammer. We clamp the piece in the vise, lay the tool steel against the part exposed from the vise and hammer against it till you get the desired bend. There is of course some art to this. We often put masking tape on the part to protect it from vise marks. I'm sure you could do all your bends like this but it would be difficult to be completely consistent.

The other thing thats nice about a scroll saw is that you can drill holes and thread the blade through them. You can't do that with a band saw.

One of the things we try to keep in mind is that the total weight of the aluminum does really add up. Putting some holes in the aluminum parts allows for more cooling for the servos and reduces weight. If the holes are placed well then they'll have little impact on the strength of the part. We calculate how many servos in weight our aluminum components add up to. It's kind of a reality check. We find it kind of surprizing how much brackets for a 25 dof robot actually weigh.

Adrenalynn
11-01-2008, 03:36 AM
More great advice!

If I may offer you something to consider: Thick leather (available as remnants) works extremely well for clamping-up parts. Non-marring (masking tape can mar if the piece slips), and doesn't leave residue behind.

I use the thick tough stuff when I'm hammering metal flat to keep from leaving pean marks too.

billyzelsnack
11-02-2008, 07:45 PM
HF $34 brake FAIL!

Maybe my expectations are out of line, but I would think it'd not have a problem with 0.063 aluminum 150mm wide. The bend I was doing was only a centimeter from the edge so it had a lot of leverage against it, but still! I'll be taking it back.

I ended up making the bends ( easily ) with a hammer and a vice. Not professional looking since you can see the hammer marks, but it is a nice bend. Maybe I should just get a second vice to sit next to my first one so I can handle wider lengths at once.

Adrenalynn
11-02-2008, 07:51 PM
Now that we know what $34 buys, may I suggest checking-out the finger brake I linked [and was further endorsed by Bullit] when you're there? :)

Oh - sorry - I mean "COMFORT! So sorry to hear it didn't work out!" :tongue: ;)

gdubb2
11-02-2008, 08:26 PM
Hey Adren.. is that a smug look I see on that smiley??

Gary

billyzelsnack
11-02-2008, 08:27 PM
I don't have a problem throwing down $200 on a tool. I just don't have a lot of space in my work area and I have to choose carefully what large tools I want to own.

I can also just continue to use my hammer and vice!

gdubb2
11-02-2008, 08:37 PM
I've made a lot of brackets with my el cheapo break. I use .050 Al then kind of rearrange the bends if needed with pieces of UHMW ,aluminum, and a small deadblow hammer. The soft face on the hammer helps with the marks.

Sienna
11-12-2008, 12:17 PM
OOO! I know what I am getting when I get my paycheck!

http://www.grizzly.com/products/12-Box-and-Pan-Brake/G0556

Its so small and cute, and at *only* 60 lbs I have a chance in getting it up two flights of stairs to the apartment!

Adrenalynn
11-12-2008, 01:54 PM
It only bends 20G. That's pretty light.

Sienna
11-12-2008, 02:31 PM
The 24" HF one linked only bends 19G, and the 24" Grizzly linked only bends 20G, so I am not sure why a 1G difference qualifies as a deciding factor. The 12" Grizzly is 1) within my ability to pick up and move and 2) within the size contraints I have in my small (overcrowded) apartment.

The thickest I am looking at bending is 1/16" aluminum. If it can handle that, its all I need.

I wish I could get a bigger brake, really, but I simply don't have the luxury of a garage or basement dedicated to large quality tools right now.

Adrenalynn
11-12-2008, 02:44 PM
1/16 is around 14G if memory serves. Aluminum is easier to bend, depending upon the alloy, you should be able to go up a couple gauges.

Modelmaker
11-12-2008, 03:43 PM
The grizzly 24" one will bend 16 gauge. you have to muscle it a bit but it can be done (I do it all the time here.

the 24" one does not weigh close to 60# I'd say 30-35 tops

Bullit
11-12-2008, 04:35 PM
Remember those gauges listed are at the full width of the brake. So unless you need to bend a 24" piece you can lower the gauge a bit. We use a similar 24" brake with 2mm or 0.080" 5052 all the time. The width of the bends are typically less then 6" though and a 6" bend would require some strength.

Adrenalynn
11-12-2008, 04:48 PM
>> and a 6" bend would require some strength

And will also tend to loosen-up the brake over time in my experience. Nothing worse than a brake that doesn't bite. . .

billyzelsnack
11-17-2008, 09:51 PM
The 24" box and pan is showing up as $199 now in the direct to store section of the latest HF ad..

http://www.harborfreightusa.com/html/special_orders/index.html?r=3325_256357

I dunno if they charge you extra to special order it. Maybe I'll find out tomorrow when I take that other brake back.

billyzelsnack
11-17-2008, 09:56 PM
Another important tool is to have either a sheer to cut aluminum sheets and/or a scroll saw to cut out your parts. We made a lot of parts just with just a scroll saw and a pan box brake.

What kind of foot do you use on your scroll saw for cutting your parts. The one on my saw is terrible. I don't know what it was designed for, but definitely not for cutting smaller metal sheets.

Adrenalynn
11-17-2008, 10:33 PM
When I was a kid, scrollsaws were called jigsaws. Sabresaws were scrollsaws... Are you operating on the older terminology? My [current] scrollsaw, aka old-skool jigsaw, doesn't have a foot - it has a table, like a miniature bandsaw...

billyzelsnack
11-17-2008, 11:39 PM
Hey! I thought I was just crazy with what I called things. Growing up I used scrollsaw and jigsaw interchangeably. After looking into it ( to buy one ) I determined that the scrollsaw was the one with the table. So yeah.. The one with table.

Adrenalynn
11-18-2008, 02:56 AM
I remember it so clearly because the name confusion/change made my dad flip out repeatedly...

I don't do anything special to cut metal on the scrollsaw - just good downward pressure to keep it from binding and vibrating. If you're worried about your thumbs, you can screw it down to sacrificial wood.

Bullit
11-18-2008, 05:59 AM
The foot is the safety bar that surrounds the blade and helps keep the material being cut from bucking up and down. I think all scroll saws have them now. When I cut sheet aluminum I turn the saw speed way down. My saw has speed settings up to 9 and I cut sheet aluminum at 2. Its a bit slow but be safe cut slowly don't cut tiny pieces. I try to cut pieces out of a larger sheet so I have plenty to hold on to. It has to remain very tight to the table so I keep both hands on the material on both sides of the blade . As Adrenalynn says you can also you a sacraficial piece of luan or thin plywood if you have trouble holding the material. You can sandwich the metal between two pieces. I don't generally use any sacraficial wood just the metal myself. As far as material jumping around, the speed of the blade, its number of teeth per inch and the blades' conditon are critical to keep the material from binding. Generally I use a 20 TPI non-ferrous metal blade at low speed. This blade is a little fast but its thicker and more rugged then the 40 or 48 TPI jewelers blades which are less likely to bind the material but they are slower and break easier too.

Adrenalynn
11-18-2008, 06:08 AM
My saw doesn't have the foot - it also is older than most of the folks on the forum and my dad bought it before I bought my Vic20. ;)

That said - great pointers, thanks!

ooops
12-31-2008, 01:26 PM
I am excited, so I will share. I have the "lil" 30" brake (2nd pic) in the shop now, and although it works OK it isn't precision by any stretch of the imagination. I have used it enough to become somewhat "addicted" to metal bending ... So I just ordered the 24" brake from HF (1st pic). If I had more room in the workshop I would have got a bigger one ... not that I need a bigger one, but isn't bigger ALWAYS better?:)

Adrenalynn
12-31-2008, 01:57 PM
Grats! When do you pick it up?

ooops
12-31-2008, 02:49 PM
Shipping was only $11.99 ... apparently based on price not weight ... so it is coming to me:)
Hopefully next week.
The sad thing is, when I go in the store I buy stuff I may never need and seldom use, just because it is a "good deal". I thought I would avoid that by buying on line, but they have the "clearance" link, and freight is so cheap, I couldn't resist adding about half a dozen other things to the cart. Shhhh don't tell the wife:)

4mem8
12-31-2008, 03:37 PM
Ha ha, [don't tell the wife] How many times have we all said that. I think I would be dead now if my wife new. ha ha. But at least she is getting a new bathroom, I love brownie points. Congrats on the brake, looks like a really neat addition to the workshop ooops.

rsqdivr
12-15-2013, 11:17 PM
if a brake is rated to bend 20ga. mild steel, what would be the equivalent for sheet aluminum that it could handle? I would think it could bend thicker aluminum (like 16ga)?