How to mark tube in fourths lengthwise.

[Greekman]

Guys i am done! wasted. I have made several sections of PVC pipe where 4 holes were to be precisely drilled around the exterior.
I used masking tape with marks but accuracy was a bit off still.

is there an easy way to mark a tube this way, without involving any math. I know the method (Pythagorean or cos of 90deg) then transfer with calipers, but i wonder if machinist have an easier one.

[Morning Sunshine]

I saw someone who made a template.... let me see if I can find a video (I actually saw it done in person, and I do not think I can describe it well)

Found it - steps 1,2,3

https://www.youtube.com/watch?v=P4d2wgo1u20
https://www.youtube.com/watch?v=HgFU8tJgNeA
https://www.youtube.com/watch?v=xErHQZ84lnE

I hope this helps with your project

[bcksknr]

     I taught art and one of the neat tricks I showed my students was an accurate way to divide any length into any number of even or odd segments. All without any math. As an example: lets say you have a 27 inch board that you need to accurately divide into 5 section (5 will not divide equally into 27). Lay the board on a flat surface and draw a straight line at right angles (90 degrees) from one end. Make this line longer than the length of the board. You should have the board and drawn line looking like a large capital letter "L".
     You now take a tape measure and put the end of the tape on one end of the board. Then angle the tape and extend it until the 30 inch mark touches the line extending from the other end of the board. You have now a triangle with one edge 30 inches long and that is divisible by 5. Mark every 6 inches along the tape (5 X 6 =30) giving you a line that is divided into 5 equal segments. Now drop a line straight down to your board from each of the 6 marks. These must by at a 90 degree angle to the board. Mark where each of these lines hits the board and it will have been divided into 5 equal segments; (in this simple example each being 5.4 inches long).
     If your working "large" you could do this on a floor with chalk. Of course a carpenter's square would come in handy, but any right angle edge will do. It sounds complicated, but try it on paper with scaled down lengths and you will see how easy it is. The beauty is that it will work for any length (within reason) and any number of divisions.   

[Greekman]

unfortunately both methods divide length wise, I want to divide around the pipe surface.

Like in this pic
https://survivalcomms.files.wordpress.com/2018/06/web-210049.jpg
I already have done it with measuring but it is very hard to coincide.

But I will keep the suggested methods noted. Some day i know i will need them.

[David in MN]

If I had to go for extreme precision I would do all the marking on my lathe and the drilling with a jig on my drill press. If I suppose you need 4 holes in line you only need 2 holes on the drill press (since it can go through both sides).

Yo uknow you could just drill through, install a slave pin and put a Wixey angle finder on the pin to get to 90. If you already had a scribe line from the lathe you'd be pretty darn close to perfect.

Enjoy googling "slave pin" I'm sure that one gets some hinky results.

[Carl]

  If more data on the desired result were given ,a better result may be forthcoming. I use slip to thread adapters  or a slightly,but tightly,smaller PVC within the larger pipe for vertical or horizontal extension and only ONE screw is then needed. A "V" rail can be made into a drill guide , or a sharp PUNCH,small drill bit ,followed by a larger ,or completed size drill bit to finish the job and larger diameter does add to finished strength.

[FreeLancer]

Make a drilling jig by cutting a square piece of 2x4, which would be 3.5 inches on each side.  On each face, draw a line that bisects each opposite corner, which will produce a perfectly centered X. Then, on each edge, find the midpoint and drill perpendicularly toward the center of the block, this will leave two holes at right angles that bisect at the midpoint of the X’s on each face. With a hole saw the diameter of the pvc pipe, drill out the middle of the block using the X’s on the faces to locate the precise center of the square. Then you can slip the pvc through the block and use the perpendicular holes drilled on the edges of the block as guides to perfectly align and drill the four holes on the pipe and keep them at perfect right angles to each other.  Drilling out the jig with a drill press would be the most precise, but even just eyeballing with a hand drill will be better than trying to eyeball and drill the pipe freehand. 

[Greekman]

David

Enjoy googling "slave pin" I'm sure that one gets some hinky results.

infact google give me a very nice video of use in gunsmithing. As no1 result!

Carl

A "V" rail

I guess you refer to the trick of keeping the pipe on a v shaped holder on the bottom. But I need a drill press for this to use.

FreeLancer
now this is a nice jig idea. still i need someone with a drill press to make it.
once I asked for advice how to mark a pipe on the length and I tried the wood with a center hole and 2 screws running down from each side of. Unfortunately I could not drill perpendicularly freehand, and this got me nowhere. failed also with a cheap drill press converter for hand drills.

[Zef_66]

is there an easy way to mark a tube this way, without involving any math. I know the method (Pythagorean or cos of 90deg) then transfer with calipers, but i wonder if machinist have an easier one.

As a machinist, the most precise way is to use an index head and a milling machine. I'm not sure super precision in marking is necessary though, if you don't even have a drill press.

[FreeLancer]

Unfortunately I could not drill perpendicularly freehand, and this got me nowhere. failed also with a cheap drill press converter for hand drills.

Get a self-centering doweling jig. Not too expensive, easy to use, perfectly square holes without a press.

[rustyknife]

Take a piece of paper about 1/2 inch wide and tape one end to the pipe. At the end of the paper near the tape mark a spot on the paper for your first hole. Continue to wrap the paper around the pipe to where it will overlap the beginning point and tape it in place. Make a mark on the overlapping part that exactly matches the first mark. Carefully unwrap the paper from the tube and lay it flat on the table. The distance between the two marks is the circumference of the pipe. You could measure the distance between the two marks and find the middle and quarter points or you can fold the paper in half to find the mid point and fold that again to find the quarter points. Hope this helps.

[Greekman]

 rustyknife
I tried this... not accurate enough they way i did it. Marker width put it off.

Get a self-centering doweling jig. Not too expensive, easy to use, perfectly square holes without a press.

aha! thanks for this find!

[Redman]

As a machinist, the most precise way is to use an index head and a milling machine. I'm not sure super precision in marking is necessary though, if you don't even have a drill press.

As a retired machinist I might say that a machinist may if no other method is available use a center head across the end, scribe a line there, turn 90* as verified with a center head and square head, scribe another line across the end and transfer the locations down the side of the tube to the desired location. Then use a V Block to hold the tube.

[Greekman]

As a retired machinist I might say that a machinist may if no other method is available use a center head across the end, scribe a line there, turn 90* as verified with a center head and square head, scribe another line across the end and transfer the locations down the side of the tube to the desired location. Then use a V Block to hold the tube.

I cannot understand this

turn 90* as verified with a center head and square head

[Redman]

Greekman this is a "combination set". The left end has a centerhead on it. The other end has a squarehead. Both are removable from the scale (ruler if you must). The  first line would be scribed using the centerhead and scale. The second line would be scribed using two scales actually, one aligned with the previous scribe marks and the centerhead and scale 90* to that one. The 90* angle is set with the squarehead.



The marks on the end of the tube then transferred to the desired location using a straight end and Keyseat gauges.



This setup will enable you to mark a line down the center of the tube to the desired location.

All that takes a bit of juggling but it can be done. Hope that makes it a little clearer.

[Zef_66]

As a retired machinist I might say that a machinist may if no other method is available use a center head across the end, scribe a line there, turn 90* as verified with a center head and square head, scribe another line across the end and transfer the locations down the side of the tube to the desired location. Then use a V Block to hold the tube.

Definitely a good way to do it as well. Not quite as accurate as a dividing/index head. But still decent.

[Redman]

Definitely a good way to do it as well. Not quite as accurate as a dividing/index head. But still decent.

Required accuracy makes a big difference in the method. Besides most hobbists wouldn't have a superspacer.

[David in MN]

Threw this out to maker friend. His repsonse:

1) rip a scrap of scrap ply or mdf to the width of the pipe.
2) Hot glue the board to the pipe.
3) Set up a fence on the drill press.
4) drill 2 holes. One with the board vertical and one with the board flat on the table.

It's the $3 dollar solution but if you spent the time to set up the fences right.. I mean you could do worse.

Not that I'm not loving learning about machining tools I will definitely be buying...

[Greekman]

now this is why this forum shines....brilliant.

BTW.... once upon a time I as considering buying my own mini-lathe, to make custom flashlight parts. Economics and available space sunk the dream.
Now I take substitutes in the form of machining projects videos from Youtube.

[Redman]

now this is why this forum shines....brilliant.

BTW.... once upon a time I as considering buying my own mini-lathe, to make custom flashlight parts. Economics and available space sunk the dream.
Now I take substitutes in the form of machining projects videos from Youtube.

  

You might be interested in this.

https://www.youtube.com/watch?v=woqegnFZl2I

[David in MN]

 

You might be interested in this.

https://www.youtube.com/watch?v=woqegnFZl2I

Great. "Remember that as machinists we aren't operators. We're there to solve problems." So true. If I only had the time, money, and space to set up a metalshop. Damn brother in law is dragging his feet getting his running and I've got some ideas to work on while he waits. And uses my woodshop. But then I just get nutty waiting and start shopping for leather tools on Craigslist because I need a new wallet.

Lest you think I jest I just used my calipers to measure my pasta roller so my homemade crackers would be rolled to the desired thickness. Yeah, I'll just make ANYTHING. 

[Redman]

Great. "Remember that as machinists we aren't operators. We're there to solve problems." So true. If I only had the time, money, and space to set up a metalshop. Damn brother in law is dragging his feet getting his running and I've got some ideas to work on while he waits. And uses my woodshop. But then I just get nutty waiting and start shopping for leather tools on Craigslist because I need a new wallet.

Lest you think I jest I just used my calipers to measure my pasta roller so my homemade crackers would be rolled to the desired thickness. Yeah, I'll just make ANYTHING. 

What's your cracker recipe? I'm retired and they won't let me run those big arse machines making stuff that weighted 5 or 6 or more tons. The boss used to bring a print around or just ask "Can you do this?". I'd just say "Hmm, come back in a couple hours boss", and  when he did come back. Got away with murder. 

[David in MN]

What's your cracker recipe? I'm retired and they won't let me run those big arse machines making stuff that weighted 5 or 6 or more tons. The boss used to bring a print around or just ask "Can you do this?". I'd just say "Hmm, come back in a couple hours boss", and  when he did come back. Got away with murder. 

I love Alton Brown's seedy crisps.

https://www.foodnetwork.com/recipes/alton-brown/seedy-crisps-recipe-1943385

More a nutty sweet cracker but I like that because it balances with a good cheese. Commercial crackers are too salty. I like the salt from the cheese. I like traditional French washed rind cow milk cheeses and Ritz just can't hold up.

I also remember the trades when I'd get a blueprint that physically couldn't exist in poured wall concrete. I was lucky in that my foreman liked me so I got the odd jobs building fountains and ramps for handicapped kids.

People who make are a dying breed.

[Greekman]

 

You might be interested in this.

https://www.youtube.com/watch?v=woqegnFZl2I

while not applicable to my needs, the fact that establishes a SURFACE made me think of this"
Since we are talking 2 opposite holes at 90 from two others, one can drop a piece of rod through the two and establish a plane/line to drill the other two at 90degs.
In my antenna build I used 3mm drill to make a hole for a 3.2mm brazing rod (radiating elements). That would make for a tight fir since drills open up a bit larger hole than their diameter AFAIK.

You might be interested in this.
https://www.youtube.com/watch?v=woqegnFZl2I

BTW i have this guy's channel bookmarked for a later date. At the moment I am watching these
https://www.youtube.com/channel/UCpp6lgdc_XO_FZYJppaFa5w/videos
https://www.youtube.com/user/Xalasis715/videos

[Redman]

Since we are talking 2 opposite holes at 90 from two others, one can drop a piece of rod through the two and establish a plane/line to drill the other two at 90degs.
In my antenna build I used 3mm drill to make a hole for a 3.2mm brazing rod (radiating elements). That would make for a tight fir since drills open up a bit larger hole than their diameter AFAIK.

 

Of course and that is probably the easiest thing for you too do.

Yes drills do usually make a hole slightly larger than their diameter.

[Redman]

I love Alton Brown's seedy crisps.

https://www.foodnetwork.com/recipes/alton-brown/seedy-crisps-recipe-1943385

Bookmarked. 

[David in MN]

Well the easiest thing would actually be to outsource to an engineering firm to develop a CAD file and 3D print the part. You might wonder why a plastic pipe with 4 holes in it cost more than your house but...

[Redman]

Well the easiest thing would actually be to outsource to an engineering firm to develop a CAD file and 3D print the part. You might wonder why a plastic pipe with 4 holes in it cost more than your house but...

Yeah that would be the easiest way no doubt. Take it a step further. Go to school and get an engineering degree, learn CAD and programing then buy a 3D printer and print the pipe with holes. You see, now the pipe can not only do what it was meant to do but has also taught new and likely valuable skills.