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Third Hand++: A multi-use helping hand for electronics and other delicate work.

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In the past I've used the third hands/helping hands available at chain electronics shops and have been frustrated with their usability. I could never get the clips exactly where I wanted them or it took more time than it really should to get setup right. I also wanted the ability to hold small circuit boards and alligator clips just don't do a very good job.

I was familiar with the adjustable coolant hose systems used to spray coolant at cutting tools in the machining industry and thought that would be a great place to start. I ordered various nozzles and hose segments from my favorite online machine tool supply company and started experimenting. This is what I came up with. While it still has plenty of room for improvement it has served me well over the last 3-4 years.

These arms can be placed into pretty much any position and they will stay there.

Another nice feature is that you can make all sorts of attachments for holding whatever you need to work on. So far I've made a circuit board holder, a clamp, a mount for an LCD, and an extraction fan for keeping fumes out of your face.

All you really need are some simple hand tools, a couple taps, a drill bit and a drill to make the basic version. If you have all the tools you need, it can be made for $20 or less.
 
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Step 1: Getting Started

Picture of Getting Started
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The first step is to gather everything you'll need.

Tools:
- Drill (A hand drill will work but a drill press would be better.)
- 3/8" drill bit
- 1/8-27 NPT tap
- 6-32 Tap
- A tap handle
- Ruler
- Center punch

Don't forget safety glasses!

Parts:
- The Base:
I used a block of 1/2" thick aluminum (5.75"x2.5"x0.5"). Aluminum is heavy enough to be stable and is easily tapped. You can use whatever you want as long as it is at least a 1/2" thick and can be tapped. (Plastic, wood, MDF, steel, etc...) The lighter the material, the larger the base needs to be in order to remain stable. If the material is too soft the threads will wear out and the arms won't stay in. If you don't have a local source for the aluminum you can order it from an online metal sales company cut to length for about $6 plus shipping. I have used www.onlinemetals.com for other projects in the past.

- The arms:
The arms are made from coolant hoses and nozzles used in the machining industry to keep cutting tools cool and lubricated. I used the Snap Flow brand coolant hose system which I bought from www.use-enco.com. They sell a "Male NPT Hose Kit" that has 13" of hose and an assortment of nozzles and connectors. That gets you most of what you need to make a two handed Third Hand. I'd recommend buying two kits and a few extra nozzles and connectors. For around $12 you will have more than enough parts to make 4 arms.
For each arm you will need:
- One 1/8 NPT connector
- 4-5" of hose
- One 1/8" 90 degree nozzle.
You may want to consider buying the hose assembly pliers for $23. They are a little difficult to snap together by hand. I didn't buy the pliers but I kind of wish I had.

- The Hands:
Each hand is made out of a banana plug threaded into the 90 degree nozzle and an alligator clip. I chose the "Flexible Banana plugs (2-Pack)" from radio shack because it has 6-32 threads that will thread into the nozzle. The alligator clips are the standard 2" size.

Step 2: Building the base - Layout

Picture of Building the base - Layout
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Once you have chosen your base material you will need to cut it to size, if it has not been done already. I used a block of 1/2" thick aluminum (5.75"x2.5"x0.5").

Next you need to layout the location of the hole for each arm. In this case I'm using three arms. The arm locations are not critical, they just need to be close enough that the hands will be able to reach each other and symmetrical so they look nice. It will also depend on the shape and size of your base material. A triangular base might also be a good way to go if you plan on using 3 arms.

Use a center punch to mark the center of each hole for drilling.

Step 3: Building the base - Drilling the holes

Picture of Building the base - Drilling the holes
I usually start with a smaller drill bit to get it started and then finish it with the 3/8" bit. Make sure you drill all the way through the material so it can be tapped. You want the hole to be perpendicular to the base so the hose connector will be flat on the surface when threaded in. This can be done with a hand drill but a drill press would be easier.

Step 4: Building the base - Tapping the holes

Picture of Building the base - Tapping the holes
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Tap the holes for the arms using the 1/8-27 NPT tap. Remember that pipe thread is tapered so you will need to tap it deep enough that the hose connector screws all the way in. But tapping it too deep will cause it to be loose and potentially strip the threads on the hose connector. Also remember to keep the tap perpendicular to the base.

I don't have a tap handle large enough for the 1/8-27 NPT tap so I used one of my sockets designed to hold taps.

If your base is metal, I recommend using thread cutting oil or any lubricant like WD-40 that you may have on hand. I use Tap-Magic thread cutting oil.

Step 5: Building the base - Surface Finish

Picture of Building the base - Surface Finish
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Now that the holes are drilled and tapped you can smooth the surfaces and round the corners using sand paper. I started with 80 grit, then used 220 grit and finished it off with coarse Scotch Brite. The Scotch Brite gives it a nice satin finish.

Step 6: Building the hands

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Remove the red and black covers from the banana plugs and discard. We only need the metal parts. Using the 6-32 tap start threading the 90 degree nozzle. The banana plug threads aren't actually 6-32 but are close enough and provide a nice tight fit. Once the banana plugs are installed you can just slide the alligator clips onto the banana plugs.

The alligator clips work pretty well as is, but they do have a tendency to rotate when holding longer or heavier items. In the next step I'll show you how to improve them.

Step 7: Improving the hands - Optional

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As I said in the previous step, the hands have a tendency to rotate on the banana plugs. While this is a feature I wanted, the ease at which they rotated was a problem in some situations. This is in part due to the alligator clips expanding when installed. You can see the gap in the picture below. To fix this I came up with a couple solutions. You can certainly skip this step and be happy with the results but doing this will make it a lot easier to use.

Metal Sleeve:
I had some stainless steel tubing sitting around that was the perfect size. OD:1/4" ID ~3/16" (0.192"). I cut a 3/8" long section of tubing and using a hammer, lightly tapped the alligator clip into the sleeve. This is the best fix in my opinion.

Wrapping with wire.
I found some thin solid core wire, wrapped it around the clip and soldered it in place. This is the easiest and cheapest solution to the problem.

Step 8: Assembling The Arms

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Unless you bought the assembly pliers($23) when you ordered the coolant hose parts, assembling the arms can be a little tricky. I didn't buy it, but here is how I figured out how to put them together with ease. Slide the parts you want to join onto a #2 Phillips screwdriver. This will keep everything aligned and all it takes is a sharp tap to get the parts to snap together. Just hold onto the hose and tap it on the work surface in the direction of the part you want to attach.

Although theses pictures show 10, I found that about 7 hose segments per arm to be about the right length. Of course that is my preference and you can use as many as you want.

Step 9: Finishing it up.

Picture of Finishing it up.
Now all you need to do is thread the arm assemblies into the base and you're done!

Next I'll show you some of the attachments I've made.

Step 10: Attachments - Circuit Board Holder

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The circuit board holder has been one of the best attachments I've made for the third hand. I've used it to hold boards as small as an inch wide all the way up to ~8 inches wide.

Making these might be beyond the capabilities of most people because of the tools needed.

I used two pieces of 1/2 x 1/4" aluminum** each about 2.5" long. In the end of each I drilled a 5/32" hole around 3/4" deep. You could do that with a hand drill and a vice but there isn't a lot of room for error. A drill press or a mill would be best.

To make the slot I used a slitting saw in my mill. The slot is a little over 1/16" wide and 1/8" deep running the entire length of the rail. I suppose you could do this with a hack saw or dremel, but it would be difficult and I suspect the results would be pretty rough.

** - Next time I would make them out of Delrin or other plastic since many circuit boards have components and traces right up to the edge of the board and could be shorted by the aluminum.

Update - Below is a picture of the circuit board holder made out of black Delrin plastic. These were a bit easier to make since I was able to use a 1/16" end mill instead of the slitting saw.

Step 11: Attachments - Fume Extraction Fan

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I made an extraction fan using an old CPU cooling fan, a bit of filter material, another 1/8" 90 degree nozzle and a couple screws. All stuff I had lying around the house.

For the filter I cut a piece of white scotch bright to the shape of the fan and attached one corner with a screw. The opposite corner I used a long screw to go through the fan and filter into the nozzle. Connect it to a twelve volt source and solder without having fumes in your face.

In my next version I plan to add white LEDs to provide extra light in addition to the extraction functionality.

Step 12: Attachments - LCD Mount

Picture of Attachments - LCD Mount
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I made this mount to hold a graphics LCD a while back when I was playing with a BASIC STAMP II.

I used a mill to build this, but I'm sure it can be done with hand tools.

I milled the black bracket out of delrin plastic, drilled and tapped the appropriate holes and screwed it to a large straight nozzle. I'm not going to get into the details as it is fairly self explanatory and not everyone is going to have the same LCD. I mostly wanted to show you the variety of attachments that can be made for the helping hands.

Step 13: Attachments - Clamp

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This clamp can be used to hold larger items than what will fit in the alligator clips.

All I did to make this was to remove the bolt at the end of the clamp and replaced it with one twice as long. Then I screwed it into a straight nozzle that I had drilled and tapped to a M3-0.5 thread.

This version can hold about 10oz. before it starts to pivot. However if you drilled a couple holes in the bar near the stationary end of the clamp and attached it to a 90 degree spray bar nozzle with two screws it could probably hold a few pounds.

UPDATE: I've made the improved clamp arm and it holds about 2.2lbs. I used a right angle adapter to make positioning the clamp easier. #4-40 screws thread right into the spray bar nozzle without having to tap them. However, drilling through the hardened metal bar of the clamp took some effort.

Step 14: Other Attachments and Ideas

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ESD
When I made the first version, which I've used for years, I was concerned with ESD and so I soldered a wire to the banana plug which ran inside the arm and was grounded to the base. I also drilled holes in the front and back so I could plug in a static wrist strap in the front and in the back, connect it to the static ground at the workbench. I probably should have soldered in a 1M ohm resistor to the wire going to each hand for more protection.

Powered Hands
I've also thought about adding binding posts to the base and wires going up to the banana plugs so that voltage can be applied to the hands for powering circuits or loads being held by the alligator clips.

The down side to the above ideas is that the left and right hands are wired to the base so changing attachments, that requires a nozzle change, means you have to disconnect the wire. However, most of the attachments I made that require a nozzle change are primarily used on the center arm. The alligator clip hands and the circuit board holder just slide onto the banana plugs so no nozzle change is required.

DMM/O-Scope Probe
I am also working on an attachment to hold voltmeter leads or an O-scope probe. I always seem to run out of hands when measuring signals on a circuit board.

Magnifying Glass
Although I never used the magnifying glass on the old helping hands I had, I'm sure many people would use one. It would be easy to adapt one to use on the center arm.

LED Light
A little extra light would be helpful as well. I plan to combine the extraction fan and an LED light.

Small Parts Tray
Below is a picture of a base that I made for a friend that has a pair of parts trays milled into the aluminum. Also below is a picture of a 4 armed version that I made for an instructables member with 3 pockets milled into the base.

Other thoughts
There are a ton of different nozzles and connectors available for the coolant hose systems. I'm sure there is no end of attachments and accessories that can be made for this third hand.
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RJBurton made it!1 month ago

Awesome idea! I cheated and bought the kit from SparkFun, mainly because the machine tools would of cost me more $$. However, the customizing is always the most fun, so I sprayed mine with high-temp grill/oven paint, added a third arm onto which I mounted an LED light magnifier from a now-redundant Harbor Freight third hand, and replaced the tiny alligator clips (worst invention ever) with some fine tip reverse tweezers. I love it! Thanks rstraugh!

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Looks great, RJ! Where did you get the reverse tweezers? I bought the hose kit from SparkFun (since they are half the cost of anywhere else), but decided to make the base as Ryan did here. I didn't realize until too late that the SparkFun base and hoses are 1/2-20 threaded rather than 1/8-27 NPT threads! So now I need to either enlarge my base holes and tap them for 1/2-20 or order new hose adapters. Another big difference I see between the kit and this Instructable is the length and connector style.The SparkFun version has hoses that are 20 connectors each with straight nozzles whereas Ryan suggests 7 and then using 90 degree nozzles, which of course would make it much harder to screw in. Which I'm guessing is why Ryan used banana plus and then squeezed them tight. But I'm curious whether you find the SparkFun arms too long?

jconley53 months ago
I accidentally bought wide nozzles and too cheap too buy new ones. Anyone have an idea how to still use them? I'm thinking of heading up the banana plug and just melting it in, good idea?

By wide nozzles, do you mean 3/4"? If yes, then you should only need to adjust the size/length/head width of the screws holding the clips and you should be golden. If you ended up with 2.5" tubes, I'm not sure that would work at all for a third hand, but you can use it to make a bench vacuum system for dust removal.

ClydeS2 months ago

Perfect! I was soooooo tired of using crappy third hands for soldering. This is just perfect.

I modified mine so that each arm is on a freestanding base instead of a fixed station. This provides much greater flexibility for the sort of soldering that I do -- jewelry mainly.

The base is made of a 1/2" cast iron floor plate, a 1/2" male adapter (copper plumbing fitting) and a 1/2" connector. I removed the "valve" piece on one end of the tube and inserted that into the connector/base along with some glue. Then inserted and glued alligator clips to the other end. I also filed down the teeth on the alligator clips so as to not mar the soft metals that I work with.

I made four of these with two being half the size of the other two, again for greater flexibility.

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Azeunkn0wn2 months ago

awesome.. materials aren't available in local stores, even ebay.ph.
where can I buy one of your work? :D

EthanJi3 months ago

very nice project. awesome!!

emkdas4 months ago

awesome one.

TomFromLSUMC4 months ago

Grainger should have them.

volto4 months ago

Awesome project. There is a commercially available helping hand tool on amazon for $50 but I'd rather build one myself like you did. One concern I have is with melting, have you had any problems with the arms melting where the alligator clips are attached from soldering heat? Thanks!

Boaticus3 years ago
Great instructable! I made the 4-armed part tray version. Also added a sheet of 1/16th thickness neoprene rubber to the bottom for more traction and less scuffs on the work bench.
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hey whats the total expensive for this project .........

£60.00 UK but I did not have to do any work. So this is expensive.

If companies sell this as a product they should include instructions. Mine did not. That is why I decided to buy the tool. So I never need to depend on others to include how to take off the ends to insert the clips. Cement blocks instead of metal seems to be a saving. However I had the plate included.

£14.29 for pliers is cheap for ease of use.

You did an amazing job on that. Just saying.
zeremy Boaticus3 years ago
i really have to have one of those trays
Archy1 year ago
I'm building the same thing, with the magnet fittings from locline instead of tapping my steel block.
However, since I'm using a 14x14"x1/4" steel panel as a workspace as well, I'd like to coat it so it's not a bare metal surface that is a) conductive b) hard (dropping delicate components) c) slick (said components rolling off, and if unbroken before, broken upon falling off the surface).
I've put a fair amount of time into googling things like "rubber metal coat", "coating metal vinyl", etc. But the best I've come up with is plastidip. It seems that plastidip is really susceptible to sharp edges, which concerns me, as removing the magnetic mounts will probably require me to leverage them against their edges.
I need a durable, soft/rubbery coating for steel.
So, any ideas for what I'm looking for, or how I can search better?
Liamthe1st Archy4 months ago

I do a little out of the box thinking Children's mats made from recycled rubber type material sold in Aldi and Lidel stores in the EU and UK of course.

I have them on my Garage workshop floor and on my work bench, nothing has ever broken these mats lock together like a jigsaw. anti slip too not sure about anti satic?

con-f-use1 year ago
Does anyone know a source for 1/8" snap flow / loc-line in the EU? I'd even be content with an online-shop that ships to the EU. Its really impossible to get the small hoses where I live.

rs-components corby uk rsonline.com starter kits and pliers

Liamthe1st4 months ago

Hello this may be useful to UK members. I just bought the modular pliers and a starter kit From RS components in the UK total cost £32.81.

I had bought the original spark-fun set from Primori.com with no instructions on taking off the conical ends and fixing the Crocodile Dog clips.

After searching two American web sites and then two Businesses in the UK

I got to a supplier I use a lot who just happened to stock them. Pliers and Tube sets. Shipping included £32.81 compared with £27.99 for the basic set with aluminium plate. No force or pressure using the holes in the base plate needed now. I can see lots being made.

uspatriota5 months ago
here is my spin on your idea...I mounted it to a lazy susan apparatus
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CarmelitoAndrade made it!5 months ago

Made a helping hand at home(kind off a remix of the above),with 3D printed parts,Pencils and used batteries .Thanks for great idea..

Here's the link - http://www.instructables.com/id/Soldering-Helping-...

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lifeinbeats10 months ago

Just ordered some hoses! Not sure what I'm going to use as a base. In order to keep costs low I'll probably find something somewhere. That's half the fun though.

I haven't got them in the mail yet, so I can't personally testify to their usability, but several of the reviews for this item mention this instructable and these being perfect for it:

http://www.amazon.com/gp/product/B008O14864/ref=ox...

They're a lot cheaper than anything else I've found out there too, and appear to use the same size thread. I'll let you know how mine turns out!

NAVET97 made it!10 months ago

More help!

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Nescafe11 months ago
rstraugh, Thanks for sharing this idea!
btaylor341 year ago
I make mine out of stone/cement
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That base looks really cool!

Thank you! I sell them on Ebay!

What are the search terms to find them on Ebay?

I think this link will do it!

http://www.ebay.com/sch/rjter50/m.html?_nkw=&_armr...

or search "third hand, helping hand"

rstraugh (author)  btaylor341 year ago
Wow, that is really nice!
iq2011 year ago
Are you selling these?
rstraugh (author)  iq2011 year ago
Sparkfun sells them. https://www.sparkfun.com/products/11784
iq201 rstraugh1 year ago

Thanks

phone geek1 year ago
I think this is a great idea and that four arms would be better.
countspicy1 year ago
I had a chance to do a sand casting at a local community college and I decided to make the base for this project as my casting. Thanks for the great instructions, I look forward to creating more attachments for this tool in the future.
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nwlaurie1 year ago
I'm very taken with this but not kitted up for drilling and tapping. I'm wondering whether this is (yet another)opportunity to get the SUGRU out! I'm going to order a 13" length of the hose material from eBay and have a fiddle.
GREAT instructible because you are SO right about the two-armed, ball-jointed, easily-broken magnifying glass type of gadget.
do you have a step by step video tutorial on how to make this? this would be very beneficial for those who are physically disabled, its an easy DIY alternative for the medical stainless steel.
vickybacon2 years ago
If you happen to be living in the US, I found a great site alternatives who also can supply affordable yet reliable stainless steel bars and other steel structures.
Malaclypse2 years ago
You would be better off getting an "R" (.343) Drill and a #5 Center Drill after using the center punch. The center drill will give you a good pilot hole and if you find one with an 82 degree chamfer on it, you will also have a good leading edge for your threads.

Although, 3/8" (.375) will work because of the nature of NPT taps, and since you aren't using it for anything but structural support, it should be fine.
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