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New Project: Plans for a Collapsible Nested Scribe
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UserPost

9:10 AM
May 18, 2010


TylerYoungblood

Guest

Post edited 9:12 AM – May 18, 2010 by Tyler


Here's one of those beginner projects that I just love. I'm all about making my own tools, even if they can be purchased for a fraction of what it costs me to make them in terms of man-hours. Why? Because I get a renewed sense of satisfaction every time I reach for a tool that I've made. My handmade tools are a constant reminder of how satisfying this hobby can be.

Mike White from the Franklin Technology Center in Joplin Missouri sent in this set of plans for a nifty collapsible scribe. What's neat about this particular scribe is it's ability to collapse down and nest inside itself. It reminds me of those hammer/screwdriver combos where the screwdrivers are nested inside the handle of the hammer. However, like many combination tools the ham-driver was never a good hammer or a good screwdriver. It was a mediocre combination of both. But I digress …

This scribe design solves the problem I have with my current $5 scribe – it protects me from getting jabbed with the point when not in use. Sure my $5 scribe came with a protective rubber tip. But I lost it within a few days somewhere in a pile of swarf. With this setup I'll be able to slip my scribe into my bib overall pocket next to my scale and never poke myself!

My only question for Mike is what method do you recommend to harden the scribe? Keep in mind that people making the scribe may have no experience whatsoever in hardening. So an explanation of the cheapest/easiest/safest technique would probably be best. Mike also shared plans for a machinists hammer (ball peen style) which I'll post in a few weeks. Thanks for sharing your plans with us Mike!

If you're an instructor like Mike and you'd like to share your student plans with the site, please feel free to submit them using the "Submit Your Plans" tab at the top of the page. I'll provide a link (and thus free publicity) back to your school or website. Every submission helps this site grow. Thank you for your support!


[Image Error: Unable to validate image details]  Scribe_Plans_from_Mike_at_Franklin_Tech.jpg (169.4 KiB, 39 hits)


Read the original blog post



9:14 PM
June 25, 2010


bvd1940

New Member

posts 8

TylerYoungblood said:

Here's one of those beginner projects that I just love. I'm all about making my own tools, even if they can be purchased for a fraction of what it costs me to make them in terms of man-hours. Why? Because I get a renewed sense of satisfaction every time I reach for a tool that I've made. My handmade tools are a constant reminder of how satisfying this hobby can be.

Mike White from the Franklin Technology Center in Joplin Missouri sent in this set of plans for a nifty collapsible scribe. What's neat about this particular scribe is it's ability to collapse down and nest inside itself. It reminds me of those hammer/screwdriver combos where the screwdrivers are nested inside the handle of the hammer. However, like many combination tools the ham-driver was never a good hammer or a good screwdriver. It was a mediocre combination of both. But I digress …

This scribe design solves the problem I have with my current $5 scribe – it protects me from getting jabbed with the point when not in use. Sure my $5 scribe came with a protective rubber tip. But I lost it within a few days somewhere in a pile of swarf. With this setup I'll be able to slip my scribe into my bib overall pocket next to my scale and never poke myself!

My only question for Mike is what method do you recommend to harden the scribe? Keep in mind that people making the scribe may have no experience whatsoever in hardening. So an explanation of the cheapest/easiest/safest technique would probably be best. Mike also shared plans for a machinists hammer (ball peen style) which I'll post in a few weeks. Thanks for sharing your plans with us Mike!

I used some stoody torch applide hardface rod for the tip and have not had to do anything to it in about 20 years! Just my 2 cents worth, hit your local welding supply for one rod it will make lots of tips.

If you're an instructor like Mike and you'd like to share your student plans with the site, please feel free to submit them using the "Submit Your Plans" tab at the top of the page. I'll provide a link (and thus free publicity) back to your school or website. Every submission helps this site grow. Thank you for your support!


[Image Error: Unable to validate image details]  Scribe_Plans_from_Mike_at_Franklin_Tech.jpg (169.4 KiB, 39 hits)


6:40 PM
July 3, 2010


Tyler

Seattle, WA

Admin

posts 1306

What's it called? Stoody torch? I'm not sure if that's a typo or something I haven't heard of before. 

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8:38 PM
March 13, 2011


car99r

Member

posts 39

Hello, I am new to the site and new to the lathe. I just purchased a Grizzly 12x36 and thought this would be my first real project. I have turned tapers but nothing to a point and as thin as the scribe. I have completed the body and cap and really enjoyed it. However, for the life of me I cannot figure out how to turn this scribe. I figured it at 3* and I turned down the 2.5" of stock to .250. As soon as I touched the stock at the 3* degree angle with cutter it bent. I have tried 3 times now with no luck….

 

Anyone willing to share some knowledge with a total newbie?

 

Thank you!

9:53 PM
March 13, 2011


sammy

Senior Member

posts 161

Car99r, welcome to the site. You ask the very question I have. I've tried to figure it out but had the same luck you have.

Sammy

9:59 PM
March 13, 2011


car99r

Member

posts 39

sammy95 said:

Car99r, welcome to the site. You ask the very question I have. I've tried to figure it out but had the same luck you have.

Sammy

Sammy,

I have been searching for hours for any videos or tutorials on turning such a fine point with no luck. Hopefully someone who has made this can chime in here?


10:01 PM
March 13, 2011


sammy

Senior Member

posts 161

There are enough experienced people on this forum that I am sure we will see the answer soon.

Samm

2:27 AM
March 14, 2011


GarethBell

Senior Member

posts 342

I'd get it close enough then use a file to finish the point.

I need a new moniker

11:36 AM
March 14, 2011


Jerry

Moderator

posts 471

Post edited 4:29 PM – March 14, 2011 by Jerry


I'll see if I have any suitable high carbon steel and look into this for you.

 

But for now, consider the relationship between speeds and feeds. In this instance that's the speed the workpiece is rotating at, and the feed rate at which we apply the tool.

Because of the fact that any given RPM the 'periphery' speed of a workpiece is determined by the diameter on a small narrow taper the speed of the surface passing a cutting tool can be very low indeed. 

A problem of perception can then occur. Whilst our chuck may be spinning at 500 rpm and would be fine on sensible diameter, with the point of a thin taper this could place needs of RPM's in the thousands to achieve the same cutting speed for a 1" bar say. So what can happen is folk feed in the tool at a 'normal' rate, but the material is not passing the tool quickly enough so digs in and it all goes pear shaped. Tiny diameters need huge RPM's.

Tools have to be sharp, very sharp, and with as small a contact patch as possible. So rough tools, forming tools, and finishing tools are usually out, we need fine sharp points. This reduces the friction, and subsequent force needed to make a cut.

Also consider, in the case of this particular need, the nature of the point design. In the pictures it appears to be a single taper to a point, whereas most commercial scribes have a secondary angle on point. This secondary angle forms the actual scribing tip, and is usually ground on, the same way a centre punch should be ground, with the grinding direction in line with the axis of the tool. I'll cover that some more when I've had a fiddle.

 

Finally, think out of the box.

If you're using the the whole taper length protruding from the chuck and expecting it to work, revisit that. A lot of machining tricks are about the application of common sense. So, in this instance, try this:

If our taper is, say, two inches long. Allow the first 1/4" to stick out of the chuck and turn it down to a fine point, leaving it slightly oversize. Then loosen the chuck minimally and pull out a further 1/4" without rotating the workpiece, turn down this section to the taper to marry up with the first piece turned. Follow this with a 1/2" bite and repeat, finally perhaps the last inch can be done to finish the roughing down. To finalise it and blend the sections finish with abrasive cloth over a file in the normal safe way. By using this method the vulnerable overhang is reduced to a place where it won't matter so much due to the increasing diameter being cut, if at all. Some experimenting with the size of bite may be needed, but it'll work far better than trying to turn the whole thing down in one setting.

12:38 PM
March 14, 2011


nick S

Manitoba, Canada

Senior Member

posts 118

Jerry, i agree with you, increase speed, and decrease overhang. Perhaps you might also have luck with a tool post grinder as well. i ground a needle jet screw for my model diesel out of an old 1/16 drill bit. i stuck my Dremel tool to the tool post, it seemed a little roughneck but it worked nicelySmile. just make sure to not over heat things, and keep that dust out of the ways!Laugh

A pessimist sees the difficulty in every opportunity;
an optimist sees the opportunity in every difficulty.
Winston Churchill

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