Willing To Teach Single PT Threading and Knurling Class

Machine Shop
#1

Hi All!

I am willing to teach a single point threading and knurling class. Say Sat July 20th. I am working on some personal projects…so might as well “kill two birds with one stone”…ugh…clichés!! :D:smiley:

Has anyone attempted to use both the large lathe and the Sherline for these functions? What are our capabilities and limits on these machines and how did they perform?

Required materials:

Dykem Blue

Single Point Threading tool profile and alignment gage

Cutting tool and cutting tool holder

Optivisor

Clean cutting fluid container

Cutting Fluid

New acid brushes

Thread micrometer

Thread (measuring) wires & rubber bands

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#2

Having done the wire and micrometer measurement I would suggest machine Shop buy a Thread Micrometer. Way easier to use and much faster.

Would this meet your needs for the class?
https://www.gamut.com/p/starrett-screw-thread-micrometer-screw-thread-comparator-micrometer-NDA0NTQ2

#3

Yes…thank you! But ratchet thimble is always best.

However, I intend to cover all aspects of threading, including roll forming, form grinding, single point threading and the use of dies along with the various measurement techniques.

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#4

Here’s another style. I’ve also used this type, I prefer the other because it is much easier (more accurate in my opinion) to get the minor pitch diameter, the major pitch is easy to get.

#5

@Chris_Wischkowsky recommend we get the Starrett. Starrett makes high quality measuring tools. This is a specialized tool but is really good for what it does - and waaaay easier than three-wire method. Unlike flat anvil micrometers, these micrometers are very easy to damage the 60 degree pointed anvils. I would keep them as Training Required tool locked up and if taught how to use in classes like threading you get access. Someone just F’ing around and going “Oh cool, check this out?” can ruin them.

Because Will is going to discuss thread form I strongly suggest we also get one of these hand held comparators. They come various screens and include this screen for wave form (also in NMW metric). You buy the basic item then the screens you want:

http://www.penntoolco.com/52-665-001/?_vsrefdom=adwords&gclid=EAIaIQobChMIjbjHhaiQ3AIVk4RpCh0k5QLmEAQYASABEgJA-fD_BwE

These allow accurate measurements of small gaps (you use grid or circulars to measure) also various angles.
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If inspecting rolled thread form, you can inspect form with having to buy expensive snap-gauges which are for specific sizes a $400-$600a pop. Although these are the standard for measuring threads in production environments … not suitable for DMS - set of six sizes in Imperial and Metric would be close to $5K plus these do have to be sent out for periodic calibration to a lab.

https://www.threadcheck.com/agd-limit-snap-gages-model-u-style/

#6

The 20th is a Friday, 21st Saturday. Just wanted to make sure you scheduled it on the day you wanted.

#7

thank you for stepping up for this. It is much needed class. I had tried to offer it before I went to nights and ended up canceling. No need to ask, just put it on the calendar. If you offer it they will come. show the process with one standard size thread you can test with a common nut unless you’re doing the internal threading as well. Every other size is the same.

the large lathe isn’t in service yet. As for the sherline, we didn’t get the (external) threading fixture. One reason is that it requires removing the motor and turning this by hand. The committee decided we didn’t want people taking anything apart on the sherline. Both the larger lathes will handle what anyone needs.

You don’t need anything fancy for making threads. thread guages are generally under $10 (saw some at CDC yesterday). these work just fine. Tens of thousands of machinist use them daily.

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OH FYI, there is/was a set in the toolbox.

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#8

Basically good for checking and sorting bolt & nut thread size. They do little to tell your much about the thread form, major and minor pitch diameter and nothing about root form.

When producing threads they are often checked for First Article Inspection and in process inspection using an Optical Comparator - 20"-40" screen at 5X-100X.

The hand held comparator will also allow you to exam the surface finish of the thread under 7X and against a template.

#9

all of this is true of course, but not everyone is building for the space shuttle.
I know only a couple of makers at DMS that are building to a +/- thousandths tolerance.
Off the shelf nuts and bolt mating parts that fit are the norm (usually +/- 030" will work).

If were just looking to buy one just because, no need to make an argument for it. Let’s just buy it. we got the money.

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#10

If people are going to begin making threads, the micrometer is a critical piece of equipment as it can indicate if the thread is to the right thickness while on the lathe and how much more needs to be taken off.

The hand held comparator would be an add-on and has uses beyond threads. A lower cost micrometer of similar anvil design can probably be found half the cost.

#11

all good in theory. when the last guy that did a successful threading class - did he have a thread mic?
has @TBJK or @BobKarnaugh who have successfully made threads on the lathe use one?
Mr Epps @billyepps who is a lifelong machininst - did you use one on a regular basis? I know I’ve never needed one. But I admit the threaded workpiece was handed over to our QC dept for validation using a larger comparator. Not that in reality there was anything we could do if they came back and said “Hey your 12 TPI thread is 12.12 TPI”. If it fit the matching part, it was a go.

It’s cool an all, but it is not a must have for making threads. NOW - you indicate it has uses beyond threads. Great! Let’s just do it. I’m just saying it’s not a must have for making threads especially in the NON-production shop that is DMS where one-of is the norm.

#12

It absolutely is not needed to teach how to cut threads.

It’s needed to see if you are making good threads.

#13

I am going to side with Nick on this one.

My intent for this class is KISS!

I would like to give a basic spiel regarding the different methods in which threads are formed and the pros/cons and purposes for those methods. This includes screw machines (Swiss machining), rolling, form grinding, single point threading and the use of taps and dies. We can also discuss class fits. Fastener locking methods and ways to prevent fastener corrosion in areas such as engine blocks. The purpose of thread reliefs. While I am very experienced in power tapping on the lathe, I will not demonstrate that subject.

We can experiment with what we have on hand. Then, depending on the outcome, we can spend $$ on tooling as required. I will be glad to demonstrate how to grind and dress a HSS tool.

We need a threading tool profile gage. This is used for both checking cutter geometry and for aligning the tool to the work. OptiiVISOR (the lighted version is nice:D:D) and a piece of white notebook paper. DYCEM is a must. Cutting fluid, clean containers for the cutting fluid and acid brushes!

The old standby method for threading long parts with overhand is to thread between centers using a lathe dog at the headstock. This way the work can be removed for inspection w/o jeopardizing alignment. The entire area to be threaded is to be painted in DYCEM. As the dye disappears, you do a fit-check to the female part.

I have a few parts that I made on the Sherline the other night, and I now need to thread them. Using a die would suffice, so I brought my own 3/8-24 hex style (1 in accross the flats). I was unable to find an appropriate die handle…do we have one?

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