DIY Wire grabbing hemostat mod - Page 1
Forum section: electronics / projects

author: robrenz
author_rank: Super Contributor
timestamp: October 29, 2012, 07:17:32 pm
content: I made a pair of these a while back and find them very usefull. Here is a simple graphic how to, I know this isn't rocket science but it might help some people.Just a hemostat with small, medium, and large diameter gripping locations. The cylindrical grip areas help to not squash the insulation especially when hot from soldering. It also takes less pressure to hold the wire securely as it is captive in an approximately matching shape.Small wireMed wireLarge wireAlso acts as a very good third hand for contact pins by just laying it flat on the table. The smooth cylindrical gripping areas do not nick the gold plating and the pin cannot pivot like they always do in a alligator clip.Start with your $3.00 Flea market curved hemostat. Look through all of them for the best ones. there is a wild variation of quality of grinding/shaping. Look for the best joint fit and general symmetry etc.The grooves can be filed in with a small rat tail file. You can gently squeeze the hemostats closed and push the file through. Only stroke the section of the file that is the right diameter for the groove you are doing.Small area done with the tip section of the file.Medium area done with the middle of the file.large area done with the back end of the file.The method I prefer is to use a dremel tool with a Harbor freight diamond mandrel of the right size at 5000 rpm. The slow RPMS give you more time to react to what is going on and make corrections. I also axially stroke the mandrel to give a better finish. I gently close the hemostats on the rotating mandrel while keeping it in the right location and axially stroking back and forth at the same time. This keeps the two halves of the cylindrical grip area aligned with each other automatically. You may need to gently influence the mandrel one way or the other to keep the depth cut into each jaw equal.SmallMedLargeUse a needle file or diamond mandrel (shown) to deburr/radius all the edges so it won't nick wires or connector pins.Use an abrasive bristle wheel to smooth/blend all the edges. Small dremel brush (slow cutting)6" diameter brush on the lathe (awesome)You may need to file the end to be flush with your first small diameter groove. Then you can file a nice rounded shape on the outside of the tip so you don't scratch or nick stuff when you are using this to cram a wire into an inaccessible area. The sanding sponge does a nice job of smoothing the file work and edges. These small finer grit ones are from the beauty shop supply stores (intended for fingernails)You have just created a thing of beautyYou can bend the arms of the hemostat so that the gripping pressure is where you would like it on the first latching position. They typicaly have way too much pressure when latched for this purpose. So bend the arms so the pressure is just enough on the first latch position (not crushing the insulation). You can always go to the second latch position if you need more grip like when holding pins to solder them.

author: Smokey
author_rank: Super Contributor
timestamp: October 29, 2012, 08:12:43 pm
content: That's a great idea. I wonder if you could do something similar with some alligator clips? I hate it when they crush the wire they are holding. Especially if it's hot from being soldered and the insulation gets all soft.

author: SeanB
author_rank: Super Contributor
timestamp: October 29, 2012, 08:19:29 pm
content: And a mirror finish as well for good looks on the outside and specially crafted grooves to grip inside as well!Lovely Robrenz, I take it you had an itch that you wanted to scratch, and this is the result.I think I must look up the prices of haemostats tomorrow or ask for the catalogue to be dropped off with a price list.

author: robrenz
author_rank: Super Contributor
timestamp: October 29, 2012, 08:32:12 pm
content: @ SmokeyGet some telescoping brass tubing from the hobby shop 1/16 ID, 3/32 ID, and 1/8 ID all with the typical .014" wall thickness. File notches into the alligator clip with a round file to match the outside diameter of each of the tubing sizes.Make it so the alligator clips hold all three tubes but still have a 1/32" gap between the jaws. Solder a piece of each tube size into the alligator clips all at the same time. Yes the alligator clip is now non functional since it is soldered shut on all three tubes. Take an exacto saw, the real thin ones and saw down thru the gap in the jaws and thru the center of each tube. open and deburr.The length of tube you use is up to you and you could do larger sizes and do more than three in a clip. Obviously this is for grabbing insulated wires since the solder will melt if directly holding a metallic pin. You could use silver solder to get the melt temperature higher than electronics solder if you want to hold bare pins.

author: robrenz
author_rank: Super Contributor
timestamp: October 29, 2012, 08:36:31 pm
content: Quote from: SeanB on October 29, 2012, 08:19:29 pmThanks SeanB, They realy are $3.00 each and 2 for $5.00 at two of our Large local flea markets.

author: andyturk
author_rank: Frequent Contributor
timestamp: October 29, 2012, 09:57:42 pm
content: Quote from: robrenz on October 29, 2012, 07:17:32 pmNudge nudge, wink wink. Say no more.

author: nanofrog
author_rank: Super Contributor
timestamp: October 30, 2012, 12:16:17 am
content: Wonderful idea, and great craftsmanship rob.Now to figure out how to make a decent 3rd hand assembly out of hemostats...Seriously though, I'd like to be able to attach them securely to segmented CNC cooling tube nozzles, but don't have much in the way of metal working skills or tools (few files, hacksaw, ... types of things and a Dremel). Not sure if I should cut one of the finger rings off or not, as I don't know if I'd be able to open them well, or how strong the arm would be in general.Ideally, would like to be able to swap them out with alligator clips or even tweezers to find the best way to hold whatever I'm trying to solder (have shaky hands).Any suggestions as to what to cut/add to make them work as I need and be stable would be appreciated. Thanks.

author: robrenz
author_rank: Super Contributor
timestamp: October 30, 2012, 11:54:44 am
content: Quote from: nanofrog on October 30, 2012, 12:16:17 amThanks, Whatever you are using to attach the aligator clips to the coolant nozzles, use the same thing and silver solder it to one of the hemostat jaws midway between the tip and the hinge. Make sure you make a right hand and left hand version (asssuming curved hemostats).

author: nanofrog
author_rank: Super Contributor
timestamp: October 30, 2012, 06:55:16 pm
content: Quote from: robrenz on October 30, 2012, 11:54:44 amThanks.Alligators can be mounted via screws to a small metal tube that's glued or screwed into the nozzle end. Figured a metal tube extending out from the nozzle, and then use a set screw to attach the intended device (hemostat, alligator, ...).But how to add this tube to the hemostat? Cut one of the finger ends off of the hemostat, form a tube over the end, and either epoxy or silver solder (have a small oxy - acetylene torch set for jewelry making)?Seems easy enough, but I'm not sure how well it I'd be able to operate the hemostat once the finger loop is cut off (disengage the locking mechanism), and wondering if there's a better approach, such as cutting a recess in the end of a metal tube (U shape in the end of the tubing), folding the upright ends over the metal shank (handle), then soldering it to the hemostat's handle (can get RT. angle nozzles instead of trying to make a bend or additional solder joint to the tubing attached to the hemostat).Just thinking out loud, and hope this is understandable without a sketch. Again, thanks for the help.

author: robrenz
author_rank: Super Contributor
timestamp: October 30, 2012, 07:29:40 pm
content: Get some 1/8 NPT female ends for your coolant lines (the yellow thing). 1/8 NPT male pipe plug with the square drive as shown. Hard silver solder/ braze the hemostat to the plug as shown. Make sure you do the opposite hand version for the other side. Screw the hemostat with plug into the coolant adaptor. Get more plugs for the alligator clips and whatever else you want to add and solder them on. Just unscrew to change to whatever you want.

author: nanofrog
author_rank: Super Contributor
timestamp: October 30, 2012, 07:46:59 pm
content: Quote from: robrenz on October 30, 2012, 07:29:40 pmWhoa. I didn't even realize that there were NPT ends for the tubing (only seen the nozzles).Seems a much simpler and easier way to go about it. Thanks again.David.