Optical Center Punch Self Holding Punch

Well I think this is a bit different than the others that I have seen. Most have several pieces. You need to align with the optical lens then switch out to the steel punch after removing the optical lens. Smack the steel punch and for the next hole insert the optical lens etc. Prices vary but up to $100.00 for a punch?
This one is self illuminating with ambient light or if you want you can use a bench lamp off to one side.
You do not have to swap out pieces of the center punch while punching.

Ok, so here is one you can make with a band saw and a drill press. I used my band saw, mini mill, and grinder.
First obtain a block of transparent or translucent plastic. (Lucite,polycarbonate,lexan). Cut out a piece about 2" x 1 5/8 x 1 3/8. Slice off a wedge at 45 degrees from the top. The 45 deg flat remaining on the main block needs to be larger than the diameter of your lens. I used my quite old Bausch 5x magnifier which is 1.045 in diameter. I stopped this bore just short of breaking out the side opposite the boring bar but let it cut out about 1/2 of the bottom. You can see the half circle in one of the pictures.

Step 2 was to drill a hole to just allow a .178 dia piece of drill blank to slip in the hole. Position this hole so it will be near the center of the half circle in the bottom of the block. Make this hole a nice slip fit to the drill blank. The punch can be most any diameter but it should be a drill blank and not drill rod. Drill blanks are hardened so you don't have to do any heat treating and annealing. I had ground a point of about 60 deg on the business end of the drill blank.

Put your lens on it and punch away. You do not need to put the optic down and pick up the punch. Just locate and punch away. Very fast. Anyhow if you make one share the build.

Cheers, JR

great tool! simple efficient, i`ll definitely make one and post here. don`t know if i`ll be able to find a block of plastic but if i can`t i`ll make it of metal and add a window for light to enter or put a small led, i`m complicating the thing but the local plastic supplier only stocks sheet (i`m on the end of the road). thanks man.
pete
now that i think maybe in the supermarket i can find something made of transparent material i can use, i`ll see

Hello Pete,
I bought my block on eBay. Price was not bad but the shipping makes it ugly. It was 10" long so I have some stock left over.
We have a container store here in Phoenix/Glendale. They have a lot of plastic stuff. Another would be Michael's craft store.

Aluminum/Brass/Steel would all work with windows. Don't even have to glaze them!

Cheers, JR

The original design works great with the Bausch & Lomb 5x eye loop. I had ordered two imports for about 1.00 each. they just came in and the focal length is different. I made up the pvc pipe adapter using a short length of 3/4 sch 40 pipe and one elbow. Cut off one socket, glued it up and just had to remove a very small amount of pvc for a sliding fit into the original optical punch block.

The optical quality of the Import is no where near the Bausch lens. It works but it is not as crisp.

Cheers, JR

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Thanks jjr2001! We've added your Optical Punch to our Metalworking category,
as well as to your builder page: jjr2001's Homemade Tools. Your receipt:

<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="http://www.homemadetools.net/homemade-optical-punch-2"> <img src="/uploads/157501/homemade-optical-punch-2.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="http://www.homemadetools.net/homemade-optical-punch-2">Optical Punch</a> <span> by <a href="http://www.homemadetools.net/builder/jjr2001">jjr2001</a></span> </div> <div class="tags">tags: <a href='http://www.homemadetools.net/tag/punch'>punch</a>, <a href='http://www.homemadetools.net/tag/magnifier'>magnifier</a>, <a href='http://www.homemadetools.net/tag/optical'>optical</a> </div> </div> </div> </div>
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Thanks jjr2001! We've added your Magnifier Adaptor to our Miscellaneous category,
as well as to your builder page: jjr2001's Homemade Tools. Your receipt:

<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="http://www.homemadetools.net/homemade-magnifier-adaptor"> <img src="/uploads/157505/homemade-magnifier-adaptor.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="http://www.homemadetools.net/homemade-magnifier-adaptor">Magnifier Adaptor</a> <span> by <a href="http://www.homemadetools.net/builder/jjr2001">jjr2001</a></span> </div> <div class="tags">tags: <a href='http://www.homemadetools.net/tag/magnifier'>magnifier</a>, <a href='http://www.homemadetools.net/tag/adaptor'>adaptor</a> </div> </div> </div> </div>
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Great idea, JR and thanks for sharing.
Since I have so much aluminum cut-offs lying around I will probably make mine out of aluminum. I also have quite a few of the cheap (free) Harbor Freight LED flashlights that are given away. I’ll put another 45 flat opposite the existing 45 degree and bore it to fit my HF light. THANK YOU for posting your great idea.

Great idea with the light. Let us know how it works out.

Cheers, JR

Thanks for the tip on optics quality. I just ordered the B&L for $8.95 on Amazon. Re-thinking this a bit; a 45 angle opposite my eyepiece may reflect too much light. I probably will make the flashlight more perpendicular (less of a 45) and off to one side. You created a great tool! All the best

Great price on the B&L. I thought the HF light might be a bit large and bright. You could use some layers of plain white paper inside the flashlight lens to reduce the brightness if necessary. Also I found some really inexpensive ones on eBay for $1.00.
They appear to be quite a bit smaller and might be easier to mount.

Useful Stream Light Micro Mini LED Super Bright Flashlights Keychain EDC Tool | eBay

Cheers, JR

Thanks for the link. Yes, the suggested Mini LED would make for a much nicer and compact device. Although I am not fond of any button style battery since they tend to be more expensive than your garden variety AAA. Good idea about reducing brightness on the HF light. The HF light is about .995" diameter which I assume is a bit less than the loupe. I'm not sure which light I will use. Also, ambient light, through an empty hole(s) may be enough. I would aim the hole(s) at the cross-hair area. Anyway, a nice project and your great idea I will get to eventually.

Another minor mod to the optical center punch. I removed a small rectangle from the bottom of the punch. I thought the acrylic line at the bottom was interfering with the sighting in of the center punch. Just used a 3/8 emd mill and put in a slot down the back side and across the bottom. Left the base nice and solid so it does not tip over.

Cheers, JR

I just received my quite small, pocketable or keychain, led flashlight from here:

Useful Stream Light Micro Mini LED Super Bright Flashlights Keychain EDC Tool | eBay

It works very well as is for a bright spot lite to see small details in your work. Have not used it long enough to judge the quality but hey for 1 buck including shipping it is worth a try.

Cheers, JR

Thanks, I will make one of these.

Thanks, for checking in. I think you will find it very useful.
Cheers, JR

I also had no ways of getting a block like that, but I have lots of old number plates I have gathered over the years, so I peeled back the sticky backing with the numbers and glued about 20 off 50 x 50 pieces that I cut from the number plates together and this is the result.
I take it it needs a fairly fast speed in the mill. I have never worked with is stuff.

Attachment 21101

Now that is a great way to get a block of plastic.
I don't remember the speed I used but it was not real fast.
In my case I step drilled to 5/8" and then bored it to eyepiece diameter.
I would start out slow and increase the speed until it starts to melt!
Then back it off a bit to prevent the plastic from melting.
A few formulas from the net. SFM for plastic about 100
R.P.M. = (3.8197 / Drill Diameter) x S.F.M.
S.F.M. = 0.2618 x Drill Diameter x R.P.M.
I.P.M. = I.P.R. (feed) x R.P.M. (speed)

I found this chart on the net which has drilling speeds for different types of material.
Drill Bit Speed

Cheers, JR

Chose a brand new 10mm end mill and the mill was still set on 900 rpm. finish was good so stuck to it. According to that chart it was smack on.

Attachment 21102

Reading my mind...:idea: my next question was going to be how to get a 20mm diameter hole for the optic. Biggest I have is a 16.

Attachment 21103

Just my sizes seeing I started with 50mm rough. It cleaned up at 47mm.

Looks good. Keep us posted.

Cheers

I don't do much accurate center-punching anymore; coordinate drilling is easier and more accurate. But, when I was starting out, I did enough of it to learn a few things that I'd like to pass along here. These are just observations that others may find useful. PLEASE DO NOT CONSTRUE ANYTHING I WRITE HERE AS CRITICISM OF JR'S DESIGN. With that said (and hopefully taken to heart by all), let me proceed.

Looking at the location of the punch tip from an angle never worked well for me. I decided that a more vertical, magnified view of the location would make things easier to see. To that end, I attached the magnifier close to the punch axis and above the punch tip.

https://s3-us-west-1.amazonaws.com/f...he/36590-2.jpg

This worked a bit better but was a bit tricky to hold; I knew there must be something better.

I realized that magnification wasn't really necessary in most cases. Almost all the prick punching was done at the intersection of layout lines. If we could locate the punch using the lines themselves rather than trying to hit their intersection, everything would be easier. So, when I ran across this commercial product...

https://s3-us-west-1.amazonaws.com/f...e/104327-2.jpg

I knew I had found the holy grail of punch locating. :-) The punch is spring-loaded and resides permanently in the base. [Thus avoiding the major complaint associated with the devices that have magnifiers and punches that must be interchanged in a single hole. A major feature of JR's design is eliminating that undesirable design feature.] Scribed in a recess in the base (see next photo) are two lines. When these lines are aligned to the scribe lines, the punch sits directly over their intersection point. A slight tap with a small hammer marks the point well enough to be found by touch with a center punch.

The recess in the base in which the lines are scribed is important. The base will become scratched from contact with metal but the lines in the recess are immune to that scratching so they will remain very visible.

https://s3-us-west-1.amazonaws.com/f...e/104327-3.jpg

I no longer remember where I bought this device so I took a photo of its box top; that's all the information I have on it.

https://s3-us-west-1.amazonaws.com/f...e/104327-4.jpg

Later I realized that, while four lines pointing at the intersection are helpful, you really only need two. This observation makes it simple to machine your own version of the device from more durable metal as I did in the photos below...

https://s3-us-west-1.amazonaws.com/f...he/54767-1.jpg

https://s3-us-west-1.amazonaws.com/f...he/54767-2.jpg

Hi Marv, I had never seen the Cosac prior to today. Nice example of a cool tool.
I like the one you designed with only a single piece of brass and the center punch.

I must make one of them..

Thanks for your input.

Cheers, JR

I never see it as criticism, there is always more that one way of doing something and the circumstances will dictate which is more appropriate to use, It is merely for you to have all these options available.
I have 4 sets of spanners and when I bought the 5th set a week ago the "other half" had a lot to say. I bought those ones with the little ratchets on the one side and normal open end on the other. Had to explain why sometimes only an open end can work, sometimes only a huge offset ring and sometimes you need very thin spanners to hold a half nut.
So from my side thanks to all out there sharing their ideas and a Happy tooling new year, :thumbsup::clapping:

Quote:

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Originally Posted by jjr2001

Hi Marv, I had never seen the Cosac prior to today. Nice example of a cool tool.
I like the one you designed with only a single piece of brass and the center punch.

I must make one of them..

Thanks for your input.

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It has a surprising second use as well. Read the full story here...

http://www.homemadetools.net/forum/o...two-uses-27184

Thanks Marv,
Excellent. That is one way to make a useful tool even more useful.

Cheers, JR

Ok, I just had to try one of these for myself and was happy to see how well it works for center punching.
Not bad for corner finding as well like Marv pointed out in this link:
http://www.homemadetools.net/forum/o...two-uses-27184
Now make that three uses with my new version that combines Marv's type with RR (Randy Richards) stamp aid
and you get this:

what are the approximate sizes there? :drool:

Quote:

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Originally Posted by garage nut

what are the approximate sizes there? :drool:

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Oops, I forgot to put in the dimensions.

The largest is the brass one. It is made from 1.25" diameter brass stock and is 1.2" long. Center hole was made for a sliding fit with a .177" piece of drill blank.
Slot is a slide fit for my stamps which came to .242" wide and about .175" deep so the stamp is proud of the top of the brass.
Under that slot is a hole made with a 1/4" drill bit for the magnet. The two milling cuts were made to the center of the hole on both the x and y axis.

The knurled steel guide is 3/4" in diameter and 1.500 inches long.

The straight steel guide is 1.250" long and 3.4" in diameter.

Same punch is used in all of them.

Cheers, JR

Thanks, great addition for the letter/number stamps.

Great project. One other approach is to simply use epoxy clear cast for the body.
I don’t have access to plastic off cuts that size, either.