Author Topic: My "Learning to use a Lathe" Journal  (Read 3806 times)

Offline MJM460

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Re: My "Learning to use a Lathe" Journal
« Reply #30 on: March 31, 2017, 10:16:19 AM »

Hi Brendon,

It is worth trying again with new hacksaw blades, though the cut off saw obviously saves time and elbow grease when one is available.  I cut quite thick steel by hand as I do not have access to an alternative, also no more room in the shop.

The hss tap and die set I mentioned (you have the right one) I have found to be very good.

The dies are not split like most, but are more interesting than that.

They are labelled g6 which is a standard tolerance grade that matches h6 taps.  Such a tolerance cannot be maintained with a split die which enables the user to adjust to a satisfactory but unknown fit.

The taps are also different.  They are marked with 1 groove on the shank, two grooves and plain, being first cut, second cut and final cut.  This is unlike the more common taper intermediate and bottom with which as Ian says you can get away with having two, which should include the bottom tap for blind holes.

The difference?  I can assure you that each of the three taps makes an approximately equal depth of cut.  You need to start with the first cut which as a longer tapered lead in to start the threads and make turning the second cut easier.  You will not be able to fit a commercial nut on after the second cut even after running the full length of the available teeth through the hole and you must follow with the final cut for final size and which is only a real bottom cut in the larger sizes.  I have had to grind the bottom point of some of the smaller ones to get deep enough into blind holes.  The cutting torque is great enough to be in real danger of breaking a tooth if you try and go straight to the final cut.

You can buy separate sets of three taps for one size and separate dies to replace the ones you eventually blunted, from the same place, but my experience is you will not need them until the original price is long forgotten.  The price for single size sets is such that the full set is better value if you need four or more sizes.  If the quality is still as good as the ones I purchased, the set is good value.  Of course it is difficult to tell, and quality from the big warehouses can vary, but they have been continuously available for many years so I assume they are always good sellers and there will be feedback if they change specification.  I hope I don't sound too much like a salesman, I am just relating my experience as a customer.

I believe the Sutton and Goliath hss tools are also exceptionally good and I have some of those for sizes smaller than the smallest in the set, and for a constant 1 mm pitch set I have accumulated for M8, M10 and M12 where the standard ISO Coarse seem a bit coarse for model making purposes.  Still not as fine as the ME 32 tip and 40 tip series, but seems to work well.  The ones available from tool suppliers seem to be the more usual taper, intermediate and bottom sizing.  I still need to buy a small number of ME sizes so I can use the commercial tails and nuts for tubing I use for my steam engines as the price makes them not worth making manually.

MJM460
The more I learn, the more I find that I still have to learn!

Offline Brendon M

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Re: My "Learning to use a Lathe" Journal
« Reply #31 on: April 03, 2017, 01:33:58 PM »
Hello MJM, thank you for replying. I have only now just worked out how to switch on thread notifications, hopefully I will appear more responsive.

On that note, Christmas has come early  ;D I picked up a new set of whitewall tyres at Springvale, and decided since I was only 15 minutes away, I went to visit the red and blue warehouse. Wow, so many lathes and milling machines! Long story short, I purchased the hss tap and die set. I got to try the M5 die and cut a thread without any difficulty. So I guess I am not simply incompetent  :)
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Offline Roger B

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Re: My "Learning to use a Lathe" Journal
« Reply #32 on: April 13, 2017, 08:04:25 PM »
Glad to see you are still at it  :ThumbsUp:  :ThumbsUp: You have probably heard/read that you should always release the tension on a hacksaw when you have finished using it. If you don't the frame distorts resulting in a wandering cut.
Best regards

Roger

Offline Admiral_dk

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Re: My "Learning to use a Lathe" Journal
« Reply #33 on: April 13, 2017, 09:02:21 PM »
Quote
You have probably heard/read that you should always release the tension on a hacksaw when you have finished using it. If you don't the frame distorts resulting in a wandering cut.

Actually no, never, not even at Technical School ....  :thinking:

But I very well adware of this being true on old "frame saws" made from wood to cut wood - and much to my dismay, all mine are gone, my sister threw them all away when she helped my father preparing his house for sale  :'(

Offline Brendon M

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Re: My "Learning to use a Lathe" Journal
« Reply #34 on: April 14, 2017, 12:42:02 PM »
Ah yes, the old "sister throwing my stuff away" story :( unfortunately I can relate.

I have actually finished machining the flywheel on my gyroscope project, I just have not had time to upload the photos. I am visiting my family and will be heading out bush for the weekend.

To summarise though, the superglue arbor/chuck worked really well, and drilling out the six holes using a milling attachment worked ok, but it makes me long for a rotary table :)

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Offline Brendon M

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Re: My "Learning to use a Lathe" Journal
« Reply #35 on: April 20, 2017, 09:13:38 AM »
Hello, I am finally getting around to the most important thing in this forum: pictures!

I'll try to keep the amount of description to a minimum

This is my first time using a so-called "Superglue Arbor".

Of note here was my difficulty in cutting the face. In the video, the face is cut by starting near the center and working outwards, but due to my tool bit grind angles, I was having trouble clearing the spigot that was being formed, so I instead reduced the outside diameter a bit at a time.

Also, my tool bit angles were not allowing me to cut into the corner. I instead plunge in a few thou and create a countersink to work around that.



Some channels to ensure that there is enough air for the glue



And it's set! It literally takes only half a minute to bond solidly.



So I turned down the outside diameter just enough to clean up the surface. By co-incidence, I'd managed to reduce to the actual 2.5 inch diameter.



And then I cut the recess. First whoops moment: forgot to measure the other side's recess depth so that at least both sides are consistent!



Next up is drilling the 6 equispaced holes. Now up to this point I'd tried a myriad of ways to index using the lathe chuck (trying to count the number of pulley teeth per chuck revolution etc), until I decided to try mounting the lot in a milling attachment, to give me both x and y movement. Mercifully, the milling attachment dial was also in thousands of an inch.



Using the plain ol' "Mark 1 Eyeball" to find the horizontal "zero". Setting the centerline height took me ages too, but I got pretty close.



A picture of the overall setup, ready to go.



Obviously, cutting the first two holes wasn't too big a deal



And here is my crude answer to the "repeatability" problem of the 3 jaw chuck: I got sick of having to re-align the drill bit (to minimise runout) every time I swapped it back in.



All 6 holes are drilled... And unfortunately there is an error with the top two. It seems I miscounted the number of turns (about 20, since the Y axis dial only goes to 50 thou!)



Oh well, that's why this is the "test piece"... Still, I love how well the Superglue Arbor works. A bit of heat from a big blow torch and it comes apart no problem.



And here is the finished "prototype"



What I've learned is: I want a rotary table I can mount to the lathe! D'oh!

Thanks for reading :)
« Last Edit: April 20, 2017, 09:50:40 AM by Brendon M »
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Offline deltatango

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Re: My "Learning to use a Lathe" Journal
« Reply #36 on: April 20, 2017, 09:54:17 AM »
The finish on the prototype wheel looks very good! I think you've learned a lot more than just the need for a rotary table.  :)

This thread has prompted me to look up Clickspring - great stuff there. Thanks for the introduction.

Cheers, DT

Offline Gas_mantle

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Re: My "Learning to use a Lathe" Journal
« Reply #37 on: April 20, 2017, 10:04:56 AM »
Hi Brendon

This reminds me very much of the same problems I was facing a couple of yrs ago when trying to make my first flywheels.

I found to get 60o spacing for the radial holes a simple way was to put a spirit level on one jaw of the 3 jaw chuck holding the work then scribe a horizontal line across the entire diameter using a scribing block. Rotate the chuck 120o and level the next jaw to scribe the next line etc.

It's not super accurate but good enough to give an even spacing to the eye on smallish wheels.

Peter.

Offline Brendon M

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Re: My "Learning to use a Lathe" Journal
« Reply #38 on: April 20, 2017, 12:05:35 PM »
In this case I was aiming for accuracy: first, to get an idea of how difficult being accurate is. Second, to minimise vibration since this is part of a gyroscope.

I was initially going to simply mark out each point, but then I thought about how much runout the small drillpress has, coupled with accurately centering the drill over the point... I thought perhaps this was a good time to learn how to use the milling attachment.
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Offline gerritv

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Re: My "Learning to use a Lathe" Journal
« Reply #39 on: April 20, 2017, 01:48:16 PM »
If you count the teeth on the gear on LH end of your spindle you can use that to index the work in chuck. Mark each of the 6 holes,(spot drill works great for this)  then move work to the milling slide for drilling.

Gerrit
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Offline Brendon M

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Re: My "Learning to use a Lathe" Journal
« Reply #40 on: April 20, 2017, 10:43:12 PM »
Hello Gerrit, this was one of the things I tried, although in this case I was counting the pulley teeth on the drive. Sadly, no combination of gears* got me a number divisible by 6.

*note: this Sheraton lathe has a gear head with 4 possible speeds.
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Offline Brendon M

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Re: My "Learning to use a Lathe" Journal
« Reply #41 on: April 26, 2017, 01:13:43 AM »
Finally found a metal merchant selling offcuts of various stuff that I can easily get to on the way to work. I was able to get a three inch aluminium pipe to build the gyroscope's frame. Naturally,  the process of drilling the two holes for the bearings is proving to be fun.

But otherwise, this project is nearing completion :) I will put up more photos soon.
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Offline mklotz

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Re: My "Learning to use a Lathe" Journal
« Reply #42 on: April 26, 2017, 03:38:52 PM »
Another way to lay out six holes on a flywheel is to take a piece of hex stock and turn a tenon to fit the central hole in the flywheel.  Loctite or superglue it in place and use it as a locator in the mill vise to orient the wheel.  After the holes are drilled, unglue the wheel with heat.
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Offline Brendon M

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Re: My "Learning to use a Lathe" Journal
« Reply #43 on: April 27, 2017, 08:10:27 AM »
Thanks for that tip, Marv. That would work really well in my case.
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Offline Brendon M

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Re: My "Learning to use a Lathe" Journal
« Reply #44 on: May 04, 2017, 10:52:10 AM »
Hello again, I am pleased to announce that I have managed to finish my gyroscope project. Once again, this project is based on plans by Clickspring Projects.

As stated in an earlier post, I finally found a metal merchant which had the stock needed to finish this project. I will attempt to summarise the rest of the build, since a better explanation exists in the form of this video series by clickspring.

I made the gyroscope frame from this piece of 3 inch aluminium pipe



First the faces were cleaned up. I then used a pipe center finder to scribe a line.



I did not have access to a mill, so the next step of drilling the bearing holes required a bit of thought.

At first I tried to hold the piece so that the pipe face was horizontal, in order to use the tailstock and spot drill to align the work. Unfortunately I've misplaced the image.

But I found it difficult to secure the piece, especially without bending it. So I tried clamping it like so and just hoped that it would be square enough.



But I found that I could not really ensure both sides would be level. Also, drilling like this meant it wanted to rotate out of alignment.



I then thought back to the video and the drilling is taking place from the top. So I changed the arrangement to match, however now I could not use the other mark to line things up. I just hoped for the best.



Clickspring does explain in this article here that the cone bearings are able to tolerate some misalignment, so I tried my best not to worry too much.

Ok, so with the holes drilled, I then "deviated" from the original plan again* by tapping both holes. (*note: totally NOT by accident). You see here my crude attempt to ensure that the tapping will be as parallel as possible.



With both holes tapped, I moved onto cleaning up the frame:



Unfortunately, a slight disaster struck while parting off:



I'm not sure what happened but the tool "bit in" about halfway through, pulling the work piece off the chuck. It might have been because I had the piece turning at 60rpm? I rechucked the frame and just parted off again to the left a bit. All this ultimately meant was a bit more to clean up.



It's not perfect, but it would do for the "prototype".



Next were the cone bearings. This was pretty straight forward so I will only show a completed one:



A shout out to my new tap and die kit, which made short work of the aluminium and brass.

Finally, I needed to cut the 60* tapers on the spindle. Unfortunately, the 4-jaw chuck was unable to grip the 1/4 inch rod. After a while of contemplating solutions, and given that it was 11pm and a 1 hour drive home, I decided throw accuracy to the wind and use the 3-jaw chuck, and see just how bad .2mm runout would be.

The answer is that there is indeed vibration, but it still works!

I have a video of it in action which can be viewed at the following url: Gyroscope video (32mb)

Here are the completed pictures:





I must say, it is incredibly rewarding to make something really neat like this gryoscope project, for the first time. I can't wait to finally get my first engine running.

Thanks for reading! :)
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