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View Full Version : Very small, left hand threading tool or 06 style inserts



txfireguy2003
01-24-2018, 12:37 PM
Hey guys, I'm trying to find a threading tool that takes the lay down triangle shaped threading inserts. Here's what I'm trying to do:

I've got a part I'm making that needs ther internal bore threaded 5/16-24. I've been drilling and tapping, using the tailstock as a guide for the tap and turning the spindle by hand. It works, fairly well, but it's slow.

What I'd like to do, is single point thread them, because I think it'll be much faster, but here's the kicker, I want to feed away from the spindle, which means I need a LH tool. I've found the RH version at Shars, but they don't carry the LH version. 1/2" shank with a thin neck to get inside a 0.250ish hole, about an inch deep. Any suggestions? Thanks.


The part I'm making is below. Also a picture of the RH version (needs a longer neck though).https://uploads.tapatalk-cdn.com/20180124/e942e9dcd627a76df05bc984ab89a032.jpghttps://uploads.tapatalk-cdn.com/20180124/edf266673f6b97ba289c8aa97cb0f036.jpg

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754
01-24-2018, 01:08 PM
Use a tapping head in drill or mill.. 150 pieces an hour or more..easy..

gzig5
01-24-2018, 02:10 PM
Wouldn't you just turn that tool upside down, and run the lathe in reverse to thread from the headstock to the tailstock? Looks like a bolt handle knob?

https://youtu.be/Z-dqOi_z5bk

LKeithR
01-24-2018, 02:11 PM
If it's a through-hole get a good quality spiral point tap, grab it with a chuck in your tailstock and power tap them at low speed
If it's a blind hole use a spiral flute tap which will tend to pull the chips out of the hole. Either way will be way faster than
single pointing. Use A9 as a cutting oil for best results in aluminum.

Using a tapping head involves a second operation. You've already got the part in the lathe so power tapping will still be faster.

If you've not done any power tapping before make a few practice runs on some scrap stock. Once you're comfortable with the
process you're off to the races. And on a side note it's generally accepted practice to use coarse threads in aluminum when
possible...

darylbane
01-24-2018, 02:49 PM
I did a couple of BSP fittings like that and used a Carmex LH holder and insert. Check MSC..not cheap though. Nikole Mini Systems may have something similar.

MattiJ
01-24-2018, 03:10 PM
Second, third and fourth vote for power tapping.SO much faster than single pointing on (manual) lathe!

BCRider
01-24-2018, 03:12 PM
Wouldn't you just turn that tool upside down, and run the lathe in reverse to thread from the headstock to the tailstock? Looks like a bolt handle knob?

https://youtu.be/Z-dqOi_z5bk

It doesn't work that way. For traversing out from the headstock to cut right hand threads you need a left hand holder with the lathe running in reverse.

From the same YT source a video on internal threads to a shoulder;

https://www.youtube.com/watch?v=k1DHKjMtdQw&t=1223s

Yondering
01-24-2018, 03:15 PM
I'm with Keith on power tapping that in the lathe; it's not hard and is way faster than single point threading. If you're really nervous about it, shut the lathe off just before pushing the tap into the work, and let inertia of the chuck & spindle do the work. You'll probably only get a few turns that way, and can work up to figuring out just when to shut off the lathe for full depth.

You can also rely on the drill chuck in the tailstock to let the tap spin as an emergency clutch if you go too far into a blind hole. Adjust chuck tension as needed; all of this is easier to do than to explain online.

BCRider
01-24-2018, 03:18 PM
Back to the OP. If you want to do the job in the lathe because it's already there then you WANT to use a tap. Especially if you're looking at multiples as you seem to be suggesting. A tap will always be WAY faster than single pointing.

If you are having troubles with the guided tap setup being awkward and fumbling with too many things and not enough hands then upgrade your tap holder setup. Use a rig something like a tail stock die holder but for a tap. A guide that slips along a center rod and holds the tap and has handles to allow you to run the tap in. To lock the spindle engage the back gear while leaving the spindle lock pin. Tap your hole, disengage the back gear and you're done. Or if it's a smaller lathe use the tap held firmly in the drill chuck of the tail stock and make up some form of handle to allow you to hand turn the spindle off a square or hex stud that locks into the tail end of the head stock spindle.

Magicniner
01-24-2018, 04:35 PM
Get a tapping head with a clutch, use a Spiral Flute tap and get stuck in. Faster than single point!

Yondering
01-24-2018, 04:42 PM
I just power tap with the tap in a drill chuck in the tailstock. It's easy, fast, and simple. No need to turn anything by hand.

txfireguy2003
01-24-2018, 05:03 PM
If it's a through-hole get a good quality spiral point tap, grab it with a chuck in your tailstock and power tap them at low speed
If it's a blind hole use a spiral flute tap which will tend to pull the chips out of the hole. Either way will be way faster than
single pointing. Use A9 as a cutting oil for best results in aluminum.

Using a tapping head involves a second operation. You've already got the part in the lathe so power tapping will still be faster.

If you've not done any power tapping before make a few practice runs on some scrap stock. Once you're comfortable with the
process you're off to the races. And on a side note it's generally accepted practice to use coarse threads in aluminum when
possible...Is a spiral flute tap required for power tapping? I had to special order the tap I have due to the non- standard thread pitch, and it's got straight flutes. There are no machine tool suppliers within an hour of me, to my knowledge anyway.

The reason for the 24TPI threads on this part is that it's an industry standard. Yes, it's a bolt knob for a rifle, and I guess some gunsmith many years ago chose 5/16-24 and it became the standard. I made one for myself, just messing around, and posted it on a Facebook group and suddenly I've got people wanting to buy one. I figure for what it costs me to make one, I'll sell as many as I can, but as with anything, the real cost is in my time since I only have a manual 12x36 lathe.

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Magicniner
01-24-2018, 05:12 PM
https://www.tracytools.com/5-16-x-24-tpi-unf?keyword=5/16&category_id=0

Enquire for spiral flute/spiral point

Joel
01-24-2018, 05:15 PM
Is a spiral flute tap required for power tapping?
Not at all. Use what you have, just make the hole deeper than otherwise necessary so the chips have a place to go (and reduce the requirement to clear the chips as you progress).

MattiJ
01-24-2018, 05:29 PM
Is a spiral flute tap required for power tapping? I had to special order the tap I have due to the non- standard thread pitch, and it's got straight flutes. There are no machine tool suppliers within an hour of me, to my knowledge anyway.

The reason for the 24TPI threads on this part is that it's an industry standard. Yes, it's a bolt knob for a rifle, and I guess some gunsmith many years ago chose 5/16-24 and it became the standard. I made one for myself, just messing around, and posted it on a Facebook group and suddenly I've got people wanting to buy one. I figure for what it costs me to make one, I'll sell as many as I can, but as with anything, the real cost is in my time since I only have a manual 12x36 lathe.

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MSC has boatload of 5/16 -24 taps. No more than 297 different models for spiral/gun point alone so I wouldn't call that special order yet!
My first try might be https://www.mscdirect.com/product/details/64938194

txfireguy2003
01-24-2018, 05:41 PM
Not at all. Use what you have, just make the hole deeper than otherwise necessary so the chips have a place to go (and reduce the requirement to clear the chips as you progress).Thanks I'll try that this evening. It ends up being a through hole anyway, but at the time of tapping, it's not, as I'm forming the knob on the end of a piece of round bar stock, drilling, tapping, polishing, then parting it off. After that's all done, I flip it around and perform a second operation to install a decorative piece. I guess I could tap during the second operation also, I just figured I'd do it this way and know for sure I'm running concentric and inline to my hole since its still in the chuck from drilling. Once I remove it and flip it, that may or may not be true with my non-adjustable 3 jaw chuck. I could always use the 4 jaw, but that negates the whole time saving aspect, and it's not critical for the second operation. I figure I can run 10 or 20 through the drilling, tapping, profiling and parting steps, then do the second operation on them all at once. Just like when I'm reloading ammo, I do one thing to every piece of brass, then move to the next step and do that to every piece of brass.

The finished product will look something like this, once I figure out the finish on the aluminum. I feel like hard coat anodizing is the best bet, but may be a little more than I want to take on in a home shop.https://uploads.tapatalk-cdn.com/20180124/a039ac4ded7c30e37d41d1dbed98cde2.jpghttps://uploads.tapatalk-cdn.com/20180124/3fd96e093aeaeb2eda4fe254df381903.jpg

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txfireguy2003
01-24-2018, 05:47 PM
MSC has boatload of 5/16 -24 taps. No more than 297 different models for spiral/gun point alone so I wouldn't call that special order yet!
My first try might be https://www.mscdirect.com/product/details/64938194"Special" order was probably the wrong term, sorry. I had to order online, because no local sources had it, but then again, basically everything for machining has been online orders for me. I'm the type of guy who wants to see it, and put my hands on it, so it's frustrating. Especially so, since I'm so new to machining and all the codes to describe the different insert shapes, sizes etc are still Greek to me. I've read and watched videos, but I just haven't used them enough to be able to remember them yet.

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CCWKen
01-24-2018, 08:23 PM
If it's a through-hole get a good quality spiral point tap, grab it with a chuck in your tailstock and power tap them at low speed
If it's a blind hole use a spiral flute tap which will tend to pull the chips out of the hole. Either way will be way faster than
single pointing.

Ditto on that. I use taps and dies on my lathe all the time. Leave the tailstock loose and let the threading pull it in.

Single pointing will take six passes. I don't see how that's faster. :confused:

JRouche
01-24-2018, 08:36 PM
Would a tapping head in the tailstock work? JR

BCRider
01-24-2018, 08:43 PM
I love the insetting of a case head in the handle. Very slick......

For a blind hole like this you really need two taps anyway. A "middle" plug tap that has some taper on the end and a bottoming tap to finish the job and extend the threading almost to the very bottom of the hole.

I honestly think that I'd still want to do this by hand using a tap holder similar in operation to the die holders that folks commonly make for their lathe. And in fact if I were making a hundred or more over the next few years I might well make a couple of them so I can have the plug and bottoming taps in separate holders to avoid swapping each time.

Rich Carlstedt
01-24-2018, 09:17 PM
Careful with that tap, the primer is still active :)

Rich

danlb
01-24-2018, 09:25 PM
The finished product will look something like this, once I figure out the finish on the aluminum. I feel like hard coat anodizing is the best bet, but may be a little more than I want to take on in a home shop.

Looks nice.

Bear in mind that the anodizing layer grows outward from the surface. When it gets to sharp corners the layer gets very thin. That's where it's most likely to chip off too. I have several flashlights with a nice black hard anodizing that look like crap when examined closely.

Parkerizing or other coating may be better.

Dan

txfireguy2003
01-24-2018, 10:20 PM
Well, I tried to power tap this afternoon, but my drill chuck doesn't have enough grip to hold the tap. It got about half way in and started spinning in the chuck. Even backing off to break the chip and going back in didn't help much, backing the tap all the way out, clearing chips and trying again didn't even get me there. I'll have to keep looking for a better way to hold the tap.

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mattthemuppet
01-24-2018, 11:20 PM
take the handle out of a tap handle and stick that in the chuck.

seriously though, get a nice new spiral flute (not point) tap made for aluminium and you'll be golden.

txfireguy2003
01-25-2018, 12:02 AM
take the handle out of a tap handle and stick that in the chuck.

seriously though, get a nice new spiral flute (not point) tap made for aluminium and you'll be golden.My chuck doesn't spin, just the tap. I'll order a new tap and go from there. I should probably get a new twist drill as well, the one I'm using is pretty short, longer than my current tap, but only by maybe 1/4". It really probably doesn't matter if the tap threads all the way to the bottom of the hole, but I'd rather have too many threads than not enough.

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LKeithR
01-25-2018, 12:22 AM
Would a tapping head in the tailstock work? JR

Not very well. When using a tapping head in a mill or drill press you have good control of how deep the tap goes and the
ability to follow the tap out when the tapping head reverses. Much more difficult to do when you're using the tapping head
on a lathe. The only time I use a tapping head is when I have a lot of small holes to tap. The ability to adjust the clutch
drag will save you a lot of broken taps. Most of the time, however, I just power tap.


...For a blind hole like this you really need two taps anyway...

Not at all. In today's world--unless you need to tap right to the very bottom of a hole--a good spiral flute tap will get you
very close to the bottom.


Well, I tried to power tap this afternoon, but my drill chuck doesn't have enough grip to
hold the tap...I'll have to keep looking for a better way to hold the tap....

You need a better chuck. If yours can't hold a 5/16 tap in aluminum it's either worn out or junk. I routinely power tap up
to 3/4" in size with a good Jacobs keyed chuck....

txfireguy2003
01-25-2018, 12:48 AM
Not very well. When using a tapping head in a mill or drill press you have good control of how deep the tap goes and the
ability to follow the tap out when the tapping head reverses. Much more difficult to do when you're using the tapping head
on a lathe. The only time I use a tapping head is when I have a lot of small holes to tap. The ability to adjust the clutch
drag will save you a lot of broken taps. Most of the time, however, I just power tap.



Not at all. In today's world--unless you need to tap right to the very bottom of a hole--a good spiral flute tap will get you
very close to the bottom.



You need a better chuck. If yours can't hold a 5/16 tap in aluminum it's either worn out or junk. I routinely power tap up
to 3/4" in size with a good Jacobs keyed chuck....That is VERY likely as it's just the chuck that normally comes with the Enco/ Grizzly/ PM 12x36 Chinese lathes.

That said, I just learned something that is probably the caused of my power tapping troubles. I had assumed that the drilled hole for a 5/16 tap was the same regardless of the thread pitch...... in doing some shopping it's not. The 5/16-18 takes an "F" sized bit, while the 24TPI version takes an "I" sized bit, which is about .020 larger......I bet if I'd used the right bit to start with, my tap would work fine.

Still, with some research, I've learned a bit about taps, and I'll be ordering the right bit, and a fast spiral flute plug tap.

Thanks for the info guys.

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754
01-25-2018, 01:04 AM
A few things here, I can't support changing the tailstock tooling every piece to avoid a second op, sorry just not fast..
Second you only need one tap not two, but it should be spiral flute.
Third post your location.
Fourth, tapping heads for lathes are different type than for drill or mill.
And regarding sliding die holder type tools I built one that easily taps 3/4 inch threads. The trick is to have a key way on it and set it so it come off the key way and rotates, this is your depth control. Fairly easy to make I xan deeribe details if needed.

txfireguy2003
01-25-2018, 09:11 AM
A few things here, I can't support changing the tailstock tooling every piece to avoid a second op, sorry just not fast..

It's not that bad really, I've got it down to one tool change, from the drill bit to the tap. Really don't need the center if I work closer to the head stock. Not really avoiding a second op, as there is a second op anyway..... just felt like it was beneficial to do as much as possible on one setup to maintain concentricity as much as possible.

Second you only need one tap not two, but it should be spiral flute.

So I've learned, thanks.

Third post your location.

Central Texas, about an hour North of Austin.

Fourth, tapping heads for lathes are different type than for drill or mill.
And regarding sliding die holder type tools I built one that easily taps 3/4 inch threads. The trick is to have a key way on it and set it so it come off the key way and rotates, this is your depth control. Fairly easy to make I xan deeribe details if needed.

Thanks, I'll look into one if I can't power tap with the drill chuck once I get the right drill and tap.




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RichR
01-25-2018, 10:54 AM
Central Texas, about an hour North of Austin.

Go to your Profile:
http://bbs.homeshopmachinist.net/members/709886-txfireguy2003
Click on the "About Me" tab and enter Central Texas in the Location field. Then click the Save button.

txfireguy2003
01-25-2018, 11:03 AM
Go to your Profile:
http://bbs.homeshopmachinist.net/members/709886-txfireguy2003
Click on the "About Me" tab and enter Central Texas in the Location field. Then click the Save button.Sorry, I tried, I'm using my phone, it won't let me follow that link, and I can't even get to it on my browser by copying and pasting.

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RichR
01-25-2018, 11:07 AM
Sorry, I tried, I'm using my phone, it won't let me follow that link, and I can't even get to it on my browser by copying and pasting.

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Try clicking on your name then click View Profile in the popup.

txfireguy2003
01-25-2018, 11:16 AM
Try clicking on your name then click View Profile in the popup.Here's the problem, I use an app called Tapatalk for forums. When I find a new forum I want to follow, it creates my account for me. When I tried to log in with the browser, it said my username or password were invalid. I can get to my profile in the app, but can't figure out how to update it. I can't even log in with the browser for some reason.

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Rich Carlstedt
01-25-2018, 11:40 AM
A quick solution if the tap turns in the chuck is to wrap the tap shank with a piece of 400 grit Wet-or-Dry abrasive paper/cloth.

Rich

danlb
01-25-2018, 12:39 PM
How do you prevent the turning tap from erasing the markings? There is nothing quite as fun as finding a nearly new tap in the drawer with a nicely smeared or sanded shaft where the 1/4-20 designation should be.


That said, I just learned something that is probably the caused of my power tapping troubles. I had assumed that the drilled hole for a 5/16 tap was the same regardless of the thread pitch...... in doing some shopping it's not. The 5/16-18 takes an "F" sized bit, while the 24TPI version takes an "I" sized bit, which is about .020 larger......I bet if I'd used the right bit to start with, my tap would work fine.

Since it's learning time... Each thread pitch uses a thread depth specific to that pitch. A 24 tpi thread on a 4 inch peanut butter jar will have the same thread depth as a 24 tpi on a 1/2 inch flashlight.

But you also get the concept of "thread engagement" with ISO / ANSI threads. Softer materials should have greater mesh between the threads and harder metals still work ok with less engagement. You simply drill a larger hole and use the same tap to get less of the thread engaged when it's screwed together. The larger hole is easier to tap and the stronger metals will still be strong enough that the bolt will break before the threads give.

The chart at https://littlemachineshop.com/reference/tapdrill.php has a nice chart that shows that for 5/16-18 you use an F for 75% thread in aluminum or J for 50% in steel.

Dan

mattthemuppet
01-25-2018, 12:44 PM
what I meant about the tap spinning in the chuck is that you could put the tap into a tap handle (without the T-handle) and then put the tap handle with tap into the drill chuck. That will give the chuck a larger diameter and softer material to grab hold of.

I made a nice sliding tailstock die holder which is dead handy, but I need to get some more tap handles and make an adapter to hold those in the die holder. that'll make power tapping super easy.

BCRider
01-25-2018, 12:47 PM
Well lookie here what You Tube turned up last night while I was randomly browsing.

https://www.youtube.com/watch?v=gPURffpoliQ&t=224s

In this version the guy mills the slot for the square tail. But if one wished they could drill a pilot hole that is the size of the square then follow with a slip fit clearance hole for the tap body. Then using a hacksaw and files form the slot on the end using the pilot size as a guide for the slot.

And I see that Abomb79 does something similar but with with round stock mild steel and a slit so it pinches the tap. The round might give the safety slip that we want but it would get chewed up pretty fast.

I wonder about the idea of an ER collet chuck with a MT shank that matches your lathe? Would the ER collets have the grip you need to hold the tap for threading but at the same time slip just a little for when the tap bottoms out? I'd still use the power then coast method so it doesn't spin excessively in the collet. And likely there would be some wear on both the tap and collet which makes the collet unusable for other things later on. But these days ER collets are cheap.

There's still that idea of a sliding slug of metal drilled on the end for the tap's shank and with a couple of set screws against the square. The slug would be large enough that you can hold it for the drive forces needed but it can slip when you hit the resistance at the bottom of the hole. The slug would fit over a 1/2" round pilot that fits into your drill chuck.

Sort of like THIS DIE HOLDER (http://bedair.org/Die/Die.html) but larger diameter and with a texture that you can grip fairly well but which won't tear up your hand when it slips as the tap hits bottom. Or perhaps this idea of riding back and forth and also spinning on the pilot shaft but with a smooth hand wheel that can spin in your grip without wearing away your hand like THIS ONE (http://www.homemadetools.net/homemade-tap-and-die-holder-for-a-lathe)

The point is that you can power tap without a fancy threading head if you can make up a suitable holder that will spin free when the tap hits bottom or is properly finished. Then turn off the machine and just back it out.

Keith, that's good to know about the spiral taps. I've seen them around but I don't have any myself. I didn't know that they are almost a bottoming tap nose shape.

Yondering
01-25-2018, 01:29 PM
If the tap spins in a decent keyed drill chuck, that's a good indication to stop there and figure out what's going on, don't try to find other ways to force it in. You guys are steering him towards a broken tap with that advice.

When a tap spins, especially in aluminum, usually either the hole is undersized and/or the tap is dull. Dull taps are pretty common, some even right out of the box, and forcing them in the hole anyway leads to broken teeth or a completely broken tap.

Joel
01-25-2018, 01:48 PM
Agreed, but in post #27 he said he was using a .2570 drill for a tap that needs a .2720 for 75% threads or up to .2950 for 65%.
That will sure make it spin, especially with the crappy factory included drill chuck he said he was using.
I didn't see it mentioned, but hopefully tapping fluid specifically for aluminum is being used.

txfireguy2003
01-25-2018, 07:34 PM
Okay so, it's probably a combination of cheap chuck, cheap/dull taps, wrong fluids, but I'll get it figured out sooner or later. When I got home from work this evening, I tried using the "F" drill bit with the 5/16-18 tap it came with (in a set of multiple sizes) and even that wouldn't power tap more than a few threads before it started spinning in the drill chuck.

My plan is to order a quality spiral flute tap (or a few), correct sized drill bit, a quality tapping fluid for aluminum, and likely a new chuck if I can find one at a reasonable price. I'm so new to machining though, the only drill chucks I've worked with have been in hand drills and cheap drill presses, so I don't really know the difference from one to another, and determining quality via an internet retail site is next to impossible. I'll have to read up before I purchase. Anybody have suggestions on what brands to be looking for in regards to all of the above items? I assumed Tap Magic for the fluid and Jacobs for the chuck, any others I should consider? What about the tap and drill bit, good brands vs junk? I'm guessing not any brand that's available at Lowe's or Home Depot, but MSC and McMaster probably don't even carry those brands. Any particular material or finish I should look for?

Thanks in advance.

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BCRider
01-25-2018, 07:51 PM
If you're doing many of them you don't really want to rely on the grip of a chuck on the tap. Once or three times is one thing. But you'll quickly ruin the chuck as well as the tap if you're doing many of these things. The jaws of the chuck are not intended as a slip clutch. The taps no biggie. Just toss it But messing up what can be a fairly costly Jacobs style chuck is another issue.

If you want to lock it solidly then look at the "tap driver" links I posted. But really if you're powering the tap into the parts without a threading head that auto stops and backs out then I'd really suggest a tap version of the axially floating die holder I suggested. The version with the smooth handwheel should do the trick. It could even be made from good plywood if you prefer. but I'd likely look around the hardware store for a wheel off something that is done in a solid material that could be adapted.

I've had great luck with both Tapzall and Tap Magic. So six of one, half a dozen the other.

754
01-25-2018, 07:55 PM
Ok guys here is the hot setup for sliding tailstock tapholders.
Lets say your sliding element has an end bore of 1.25 where the tapholder fits in.
You make a top hat bushings like so.
Machine a section of the holder about 1.25 long to 1.248, the lip past this must be larger. While still set up, bore for tap shank size plus 2 thou. Generally they are oddball sizes.
Then take the whole workpiece, over to mill or drill, approx .3 from end drill a through hole on center, thru the center hole and out the other side. Must be tap drill size and you will need two setscrews, to install after tapping. Now on the side of the 1.248 portion, mill a flat about 3/8 wide, up to the bigger shoulder, but not into it.
Now part off the finished tapholder , chamfer the bore.
Now you can slide your tap in and tighten the 2 setscrews, which hold the square portion from turning.
Now it ready to go in the sliding element, near the end you will drill and tap for two setscrews. This now locks your tapholder into the sliding part. As I mentioned I have a keyway to drive mine, and ut has a Morse 4 mount to fit the tailstock. 3/4 inch thrwading under power is easy with this.

Joel
01-25-2018, 08:49 PM
For 10 parts, I probably wouldn't bother waiting for a more suitable tap. Just run it in several threads under power (to assure a straight start) and finish with a tap wrench. You will likely want to put the lathe into the lowest gear. It shouldn't add but a couple of minutes per part.
My go-to chuck is a ball bearing 5/8" Taiwanese I got from Enco for not much money. Perhaps others can suggest the best place to currently get something similar.

Jim Stewart
01-25-2018, 09:21 PM
Tx, do I remember correctly that you're using a straight flute tap?

I recall someone saying you can power tap with one, but I can't imagine how unless you're using a (rather sophisticated) tapping head.

I power tap all the time in the lathe or mill just using a good Jacobs chuck to hold the tap (not too tightly so it'll spin if there's a problem). But I use spiral point taps (in a through hole). They'll work in a blind hole if there's enough space beyond the tapped area to hold the chips.

For blind holes I don't have any spiral *flute* taps which suck the chips out the back like a twist drill, but they're very effective (although, some say, rather brittle).

I have never used a straight flute tap that didn't have to be backed off every 1/4 to 1/2 turn to clear the chips.

-js

754
01-25-2018, 09:41 PM
There are a few threads that are hard to find on machine taps.
I used to do a lot if 3/8 NPS F threads with straight taps, they reauired constant backing off.. could not use my tapper.
So I took my sliding tailstock tapper, made a tap holder. Then I made a tri bar spinner that fit over the sliding part and fastened it to the sliding tap holder. Then I pulled the key out of the keyway, so it as in full spin mode.
Then I chucked the bushing and turned holder with tri bar, backing off frequently. A bit slow but worked well.
Would have been far easier to do, if I could stand on the back side of the la them but had no room.

dneufell
01-25-2018, 09:53 PM
micro 100 bore bar.........:)

754
01-25-2018, 09:59 PM
Bokum make micro boring and chamfering tools. Great stuff.
Not cheap but excellent quality that can be sharpened many times.
I used their chmfering tools in a slide toolholder to cut a parts back inner chamfer, BEFORE parting the work off. Also used a back slide tool. Made washers .200 thick out of 3/4 bar. When I parted them they had all 4 chamfers.

dneufell
01-25-2018, 11:30 PM
duhhhh........micro 100 lh thread bar
:)

Yondering
01-26-2018, 12:00 AM
Txfireguy - for cutting fluid, good old WD-40 is pretty darn good. Some say A-9 is better, but I haven't found that to be the case in my experience. Either one is much better than dry.

From what you describe - yeah your tap is probably dull. With a sharp tap (even if it's only a spiral point tap, which is all I use) you should have no problem power tapping that in the chuck you have. I really doubt you need to replace the chuck unless it's actually worn or shows other signs of problems. You may need to clean some oil off the gripping surface of the jaws though. I eventually had to replace my Jet chuck, but because it got bound up inside, not for extra gripping power.

If you're not clear on power tapping - the tap is in the tailstock, and the tailstock is NOT clamped to the ways, just sliding. Make sure the ways are clean and oiled so it slides easily. You just push the whole tailstock to feed the tap into the part, and I'd start with shutting the lathe off right before the tap makes contact, if you're running ~800 rpm or so. Once it stops, run the lathe in reverse and pull the tailstock back by hand. If your lathe has a brake, the whole thing is even easier.

The goal is to be able to tap the hole without the tap spinning in the chuck - that ability to spin is just a backup in case you go too deep, not something to do every time. Obviously, drilling the hole extra deep is helpful if the part allows it.

With the right size drill bit, a sharp tap, and some WD-40, this really is a pretty simple operation, and one of the easier parts of building what you're doing, once you get the hang of it.

txfireguy2003
01-26-2018, 12:40 AM
Sorry if I haven't said this already guys, but thanks a ton for your help.

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danlb
01-26-2018, 01:06 AM
It's always fun to try to help. Even when the advice is half wrong, we do try!

MattiJ
01-26-2018, 03:26 AM
If you're doing many of them you don't really want to rely on the grip of a chuck on the tap. Once or three times is one thing. But you'll quickly ruin the chuck as well as the tap if you're doing many of these things. The jaws of the chuck are not intended as a slip clutch. The taps no biggie. Just toss it But messing up what can be a fairly costly Jacobs style chuck is another issue.



And use key drill chuck if you want to rely on it slipping.
My cheapo keyless chucks slip almost every time its not supposed, :rolleyes: until the one time when it self-tightens to a death grip on the tap shank. :p

Yondering
01-26-2018, 03:17 PM
And use key drill chuck if you want to rely on it slipping.
My cheapo keyless chucks slip almost every time its not supposed, :rolleyes: until the one time when it self-tightens to a death grip on the tap shank. :p

Yes, keyed chuck for sure. And as I said before, the goal is to not have the tap slip. If it does slip, you're doing it wrong, but the slipping just saved you from breaking the tap.

txfireguy2003
01-31-2018, 08:33 PM
Well I ordered a few things for this project and they are slowly starting to trickle in. I got them off Amazon because I had gift cards to burn, so they are shipping from multiple sources. Today, the Tap Magic came in ance I couldn't resist trying it to see how much difference it made. Wow, I couldn't believe the difference! I've been using either WD-40 or a heavy dark cutting oil, the name escapes me. It's amazing how much difference using a cutting fluid specific to aluminum makes. Now I can't wait until my quality drill bit and tap come in, and the new drill chuck.

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txfireguy2003
02-02-2018, 08:38 PM
My new drill bits came in yesterday and the spiral flute tap came today..... holy hell, amazing what the right quality tools will do for you! I'm not sure where parabolic drill bits have been all my life, but the chip evacuation and speed of drilling is amazing compared to my standard bits. If my new chuck would just come in, maybe I could realize the full potential, since this one keeps slipping.

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