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Dan_the_Chemist
01-27-2019, 02:38 PM
In making my CNC router I'm going to be tapping lots of holes. LOTS of holes.

(cue up the music from "The Music Man")
Why sure I've hand tapped holes,
Certainly mighty proud I say
I'm always mighty proud to say it.
I consider that the hours I spend
With a tap wrench in my hand are golden.
Help you cultivate horse sense
And a cool head and a keen eye.
(cut music)

But when talking hundreds of holes I begin to think of the desirability of power tapping. One thing makes me hesitate - I have never done power tapping.

So folks, I need to learn about power tapping. Does one have to use an alignment feature such as a mill, or can one use a hand drill? (I have both, but I am not going to get the 45" by 68" 1" thick Aluminum table onto my mill). If using a hand drill does the risk go up a lot? Do you use the same size drills for drilling the hole prior to machine tapping as one does for hand tapping? Does one need spiral taps? Why spiral taps? Are Chinesium spiral taps as good as USA-ian taps? Any recommendations as to where to buy spiral taps (if needed)? How risky is it - what are the rates of breakage? Any hints on how to avoid failure?

:confused: Help me people... :confused:

BCRider
01-27-2019, 02:55 PM
Even a short "thread crest" sized lead in towards the tapping hole can be pretty effective at lining up the tap for a good straight thread. And doing it that way has another advantage. It avoids any potential slight outward bulging of the metal that would tend to concentrate the holding pressure to the area right at the bolt instead of spreading it out for a more stable retention.

How much of a crest sise lead in? I'd say one diameter would be more than is needed but would certainly line things up really well. Likely half to maybe 2/3 of a bolt diameter would do just lovely.

Another option that could aid with power tapping with a hand drill is to set up a few taps and grind a short parallel pilot on the very nose of the tap that matches the drill size used for the tapping holes. If you make the drilled holes deep enough so that you can use taper taps there's still lots of lead in even after a short pilot section. Like just a couple of mm's worth.

If you do both I'm thinking that a half diameter lead in combined with a small smooth non cutting pilot would pretty well ensure really nicely centered threads done using a hand drill on slow high torque range.

Drill chucks don't hold taps well worth a darn either. So you'll want to grind three evenly spaced flats for the hand drill jaws.

You still need to do a good job of drilling the holes though. If not in a mill then you're going to need to make up some drilling jigs to ensure straight "square" holes. Jigs with hardened drill bushings. And if you use such jigs and bushings you may as well use the same jigs as tapping jigs with suitable size bushings. At least to start the threads. And then finish them without the jigs.

old mart
01-27-2019, 02:56 PM
My old firm had a couple of these pantograph tapping arms with reversible pneumatic motors on them for the odd times when the CNC's only produced the untapped holes. They are not cheap, but it might be possible to make one.https://www.ebay.co.uk/itm/ARM-950-12-Tapping-Machine-Pantographic-Arm-/152891992177

RB211
01-27-2019, 03:15 PM
Gun spiral tap in a drill. If the holes are thru hole, makes life much easier. Gun spiral taps I am thinking, draw the chips out as you thread. Get a high quality USA/Japanese tap if HSS.

Doc Nickel
01-27-2019, 03:32 PM
My old firm had a couple of these pantograph tapping arms with reversible pneumatic motors[.]

-I was going to suggest something like that. If you have that many holes to tap- several hundred, it would appear- it would be worth it to buy a machine like that, fixture everything as needed to be able to use it, buy some high quality, name-brand taps, and use some name-brand, specific-purpose tapping fluid.

If it were me, I'd probably even do something like swap out for a fresh tap every 50-60 holes, too.

And once you're done, if you don't need the tapper anymore, sell it off to recoup some of your costs.

Trying to do it in an unsupported cordless screwgun is just asking to leave a couple dozen broken taps in the assembly, and have half the holes tapped slightly crooked.

Doc.

Noitoen
01-27-2019, 03:34 PM
You can use a cordless drill with a guide like a wood router base.
https://goo.gl/images/v571Ua

small.planes
01-27-2019, 03:49 PM
For M5 and up I just use a cordless drill freehand.
For M4 it depends a little on the project and material.
M2 and below I am very careful and usually use the mill as a tapping guide.
Generally reasonably good quality progressive HSS taps - like these:
https://www.arceurotrade.co.uk/Catalogue/Cutting-Tools/Taps/Serial-Hand-Taps-Metric-Fine

Dave

mickeyf
01-27-2019, 03:54 PM
And of course if you do it with a hand drill, practice first on a piece of scrap.

MattiJ
01-27-2019, 03:57 PM
Like mentioned many drill chucks don't hold tap worth a hoot. But for aluminium with sharp tap it should work. I use also cordless drill&chuck for steel, works as a overload clutch before breaking the tap. Chinese taps need more torque and almost always slip, whereas sharp free-cutting DC-SWISS doesn't slip.

Noname chinese taps are too much lottery, some of them work but you better of by buying good brand name taps.
Gun point aka spiral point for trough holes(or holes with excess depth) and spiral flute for blind holes.

Noitoen
01-27-2019, 04:07 PM
One coat of aluminium tape on the tap shank helps the chuck grip.

BCRider
01-27-2019, 04:14 PM
Gun spiral tap in a drill. If the holes are thru hole, makes life much easier. Gun spiral taps I am thinking, draw the chips out as you thread. Get a high quality USA/Japanese tap if HSS.

These work really well with power tapping too. The spiral makes the taps tolerate the higher torque more easily and with less risk of an "oopsie".

Having bought and used the cheap taps, which are all from China these days, I STRONGLY recommend buying good taps. China makes good ones too but at a higher price than the junk options. But normally buy a good "name" brand to be sure you get a properly ground and relieved thread tap. They're WAY better. Plus a good name brand will let you get a lot more holes per charge on the pack if you're running a battery power drill.

The bit about the aluminium duct tape is interesting. I'll have to try that. I suspect it would rip away after a few holes though. Might be great for one or two but 30 or 40?

Joel
01-27-2019, 04:19 PM
Use a tap guide block.

Put a healthy chamfer on the drilled hole.
Drill a hole that fits the tap in a block of aluminum.
Make an adapter for the drill to fit the tap (slip fit would be much faster and adding a magnet would help retention).

So, you would put the block over the hole and get the tap well-started straight.
Slip the adapter off the tap and pull the block over the tap.
Put the adapter back on the tap and finish the depth.
Back out and go to the next hole.

For short threads, one can use a shorter block - then the tap can just stay locked in the drill.

Tundra Twin Track
01-27-2019, 04:22 PM
I use cordless drill a lot for tapping,if holding tap is a issue Tap Sockets are real handy.I use a small container for tapping lube and with the drill running in low range dip it in and while it still running tap your hole.This keeps the entire tap lubed,I use Sowa taps mostly taper point & spiral flute.For that project I would reccomened high qaulity Taps.

wierdscience
01-27-2019, 04:25 PM
You can use a cordless drill with a guide like a wood router base.
https://goo.gl/images/v571Ua

x's 2 for the drill guide.Also I would buy quaility taps made specifically for Aluminum,either that or fluteless taps.

For driving the taps,these Lisle tap sockets work great-
https://www.lislecorp.com/specialty-tools/tap-socket-set

oxford
01-27-2019, 04:28 PM
I have tapped hundreds if not thousands of holes with a hand drill, I have also broke my share of taps doing it. If through holes and above 1/4” it should be no problems in 1” aluminum plate with a hand drill. Under 1/4” down to 6-32 I would still do with a hand drill you just need to take a little more caution, same with blind holes.

Get a good quality spiral point tap for through holes. I wouldn’t mess with chi-com ones, 1 or 2 taps will get you through the job. Also mentioned, the drill chuck will not bite into the tap all that well. I currently use a tap in a tap socket and then a square drive to hex adapter in the drill. You would also be surprised how well you can get the drill chuck to grip onto the square end of the tap. Put one jaw of the chuck directly onto one of the flats and then grip down. You have to move the tap around a little but it will run pretty true.

deltap
01-27-2019, 04:34 PM
I have used a hand tap wrench, the kind with the tightening nut on the end. Remove the cross bar and insert in battery drill. You can make a tapping block to get started straight. Through holes and gun tap to drive chips ahead will make job easier. Should work in AL up to about 3/8 tap. WD 40 for tapping fluid. You don't need 1 inch of thread so you could drill a giude hole on top and use longer fastener. A mag drill on a steel plate clamped to the AL might work. A vacuum hold down could also work.

Tundra Twin Track
01-27-2019, 04:57 PM
These are Aluminium Taps prices are cdn.https://i1371.photobucket.com/albums/ag292/tundratwintrack/image_zpsuu1qtzgw.jpg (https://s1371.photobucket.com/user/tundratwintrack/media/image_zpsuu1qtzgw.jpg.html)

danlb
01-27-2019, 05:02 PM
I am notorious when it comes to drilling holes at an angle. Not much better at tapping. Using the mill or drill press makes all the difference in the world.

If you will be drilling hundreds of holes you might consider the sturdier alignment guide that is similar the one Noitoen gave a few posts back. The Portalign tool works a little different in that it has a spindle with bearings. To use it you would normally need a drill with 3/8x24 UNF chuck. You remove the chuck from the drill and put the Portalign in between the drill and the chuck. Its not easy to remove the chuck from the drill, so you will probably have a dedicated drill for this duty.

https://www.ebay.com/itm/Vintage-Portalign-Tool-Co-Precision-Drill-Guide-w-Craftsman-Chuck-29751-NO-KEY-/192776697262

http://mypartition.com/images/PortalignAttachment.jpg

darryl
01-27-2019, 05:24 PM
For that many holes- and probably drilled twice each as well (pilot, then tap drill size) you might be better off making a drill press stand to hold a cordless (or corded) drill. I'm thinking a rectangular piece of flat stock as a base (some of that aluminum you have would be great for this), use two columns near one end with a sliding holder for the drill between them. Make a cutout in the base where the drill or tap would come down (so you can see what you're doing). This you can use on any flat surface when you want to make sure you're drilling straight and perpendicular.

Use one hand to hold the base in position, and the other to operate the drill, the reverse switch, and provide the up/down motion. If you don't have to worry about keeping the drill vertical you can concentrate more on the actual drilling and tapping.

A corded drill might be best for this since they often have features in the body that facilitate mounting them in a press of some kind. You'd probably want to avoid trying to use one of those drill press stands as they would be too clumsy to use the way you want to- though one of them might provide parts for holding the drill.

You have one hand holding the base down, and only one other hand to work the drill. You would want to push/pull the drill up and down directly, without having to use a lever arrangement. With the right drill this mechanism would be simple to make, and it will always be useful. You will thank yourself for taking the time to build this.

Something else I've found is that often a corded drill will have a smoother trigger for variable speed. Maybe this is just my experience, but it's nice to have smooth control at lower speeds- it's also nice to have a reverse switch that's fast and easy to use.

Danlb showed the basic idea above. I wouldn't use a round base though because if you're drilling close to an edge, much of the base is hanging off the work piece. The rectangular base allows for almost all of the base to be in contact with the work piece, giving less chance for a rocking motion to screw you up. Also, I would be happier to also support the rear of the drill between the guides so there's less chance of it cocking sideways. The columns might have to be longer.

Rich Carlstedt
01-27-2019, 05:55 PM
Here is a trick for you if you ware worried about breaking and 'Removing" a tap
Before you start, grind a grove around the shank of the tap. The grove should be less than the root diameter of the thread plus some.
If you get to a point where a tap will break, it will break at the groove and then you have some shank stub to work the tap out.
Remember taps break at the least material condition ( flute root) where the greatest load (torque) is and that is usually the surface point.
If the groove has less material, that is where failure occurs. It looks ugly but will save your butt !

Rich

oxford
01-27-2019, 05:56 PM
If you don’t have the plate yet and really have hundreds of holes to tap in a 45”x68” piece I would consider getting some quotes on having the plate cut to size and the holes drilled in it. I don’t think there would be a huge cost in having this done and would assure the holes are all straight and exactly where you want them. Being aluminum it should be able to be done on a CNC router which may be the cheapest option.

epicfail48
01-27-2019, 06:00 PM
Gun spiral tap in a drill. If the holes are thru hole, makes life much easier. Gun spiral taps I am thinking, draw the chips out as you thread. Get a high quality USA/Japanese tap if HSS.

Issue on terminology, gun taps refer to spiral tip taps, where the spiral is cut so it 'shoots' the chips forward in the hole. Great for through holes, as mentioned, but not what you want for blind holes.

RB, im assuming that you know this, but i dunno that the OP does, and dont want someone to make the same mistake that i did... Dont assume that "spiral tap" and "spiral flute tap" tap are the same thing! Personally, i prefer the spiral flute taps that draw the chips up and out of the hole, like a drill bit. Maybe not as good as a gun tap for through holes, but better than straight flutes by miles and make power tapping a breeze

oxford
01-27-2019, 06:24 PM
Issue on terminology, gun taps refer to spiral tip taps, where the spiral is cut so it 'shoots' the chips forward in the hole. Great for through holes, as mentioned, but not what you want for blind holes.

The sprial point taps do ok on blind holes as long as you can drill the hole deeper than what your intended tap depth is(drill it deep enough so the chip has someplace to go). Getting the chip out is sometimes fun especially on smaller holes.

J Tiers
01-27-2019, 06:53 PM
Depending on how critical the tapped hole sizing is (class of fit), there are combined drills and taps in the common thread types. They cut the time a LOT when you have through holes in material that is not so thick.

The cost of cutting the time is that you need the ability to stop the driving motor instantly, you do not want to run the tap part in all the way, as that can/will break the tap on most of the sizes I have used.

oxford
01-27-2019, 07:06 PM
Depending on how critical the tapped hole sizing is (class of fit), there are combined drills and taps in the common thread types. They cut the time a LOT when you have through holes in material that is not so thick..

I have used these in the past, mostly 10-24 on tubing. They do cut down on time quite a bit but require a little finesse. You have to be careful of drill break through and how much pressure you are putting on when it happens, you can break the tap easily. The ones I used also had a build in chamfer tool on it as well and another plus is the drill part is harder than a normal drill so it stays sharper for a lot longer.

Noitoen
01-28-2019, 02:07 AM
I think tap with drill is just for thin plate

RB211
01-28-2019, 04:11 AM
Issue on terminology, gun taps refer to spiral tip taps, where the spiral is cut so it 'shoots' the chips forward in the hole. Great for through holes, as mentioned, but not what you want for blind holes.

RB, im assuming that you know this, but i dunno that the OP does, and dont want someone to make the same mistake that i did... Dont assume that "spiral tap" and "spiral flute tap" tap are the same thing! Personally, i prefer the spiral flute taps that draw the chips up and out of the hole, like a drill bit. Maybe not as good as a gun tap for through holes, but better than straight flutes by miles and make power tapping a breeze

Thank you, I meant to say spiral flute tap, I never made that connection before. Learned something new.

Arcane
01-28-2019, 04:52 AM
I think tap with drill is just for thin plate

Yeah, I have one for 3/8" -16 and the length of of the tap portion including the tapered lead-in is just one inch and the maximum effective tap length is 3/4". It wouldn't work for 1" thick plate but a 1/2" - 13 (https://www.acklandsgrainger.com/en/product/TAP-%2B-DRILL-1-2-13-NC-HSS/p/CSBDT02408) one might. I don't have one but from the picture in the link the shank looks like it is smaller than the drill size (0.435) but that's something that would need to be double checked.

Beazld
01-28-2019, 06:22 AM
Cordless tapping tool

https://www.metabo.com/us/index.php?lang=23&cl=details&aid=8_603828890&anid=8_603828890&fnc=outputSpecSheet&am=1&cnid=8_26987&listtype=list&actcontrol=oxwarticledetails&stoken=
https://m.youtube.com/watch?v=oBIvfO0sDkM

J Tiers
01-28-2019, 11:05 AM
I think tap with drill is just for thin plate

True. The drill portion must pass through the material before the tap starts to cut. The drill cannot cut at the rate of advance that the tap cuts per turn.

Noitoen
01-28-2019, 11:19 AM
True. The drill portion must pass through the material before the tap starts to cut. The drill cannot cut at the rate of advance that the tap cuts per turn.

That's what I thought;)

J Tiers
01-28-2019, 12:24 PM
The thickness you can use them in is set by the distance from the drill tip to the start of the tap portion. That can be as much as 12mm or more.

Dan_the_Chemist
01-28-2019, 01:26 PM
Thanks guys...

To summarize:


A two flute spiral tap is the best

get good ones, it pays
coated for aluminum would be nice but not necessary
consider modifying a taper tap by grinding a lead-in with OD == dia of pilot drill hole
Nothing special about drilling the tap pilot hole (other than get it in the right place and drill it straight and square)
Making sure that the axis of the tap is aligned to the axis of the hole is crucial. Thus one should use one of

mill or drillpress when reasonable
pantograph (pricey)
small guide to hold a hand drill
guide block similar a drill guide
skill and luck
Hand drills may need the assistance of

3 ground flats
aluminum tape
Use tapping fluid
Practice on some scrap
If I find I am breaking taps a method for grooving the shank may prove beneficial for extraction


While one person mentioned the $300 drill and attachment from Metabo, nobody mentioned a TapMagic or similar gizmo. Is that because they are so expensive, or not that great for the price?

Is that a reasonable summary?

So it looks as if my current plan

I will use my B'port when possible. Drill per normal, back gear for tapping.
Otherwise a hand drill with guiding jig or at least use guide blocks. Slow speed for tapping.

Might grind

three flats to help hold tap
a lead-in on a tap for hand drill use
Use cutting fluid.



Thanks again guys.

MattiJ
01-28-2019, 01:40 PM
part C. Don't be too shy or overcomplicate things.

This is how its done:

https://www.youtube.com/watch?v=E3_j5YMRENY

Chinese tap, wobbly adapter, one-handed, 10mm steel plate with full(75%) thread. ;)

754
01-28-2019, 02:20 PM
Unless you got a clutch I would never put flats on it.
If you must and have a spin index it's easy, but I would rather slip a tap than break a tap.

Not sure if you have access to a Bridgeport , but it should do it split into 1/4 section, should that that for each setup. Use spacers underneath. Drill all the holes on the mill in one 1/4 of the plate, then tap, then reset to the other 1/4,s.
Try to borrow a tapping head. ..

epicfail48
01-28-2019, 02:52 PM
I wouldn't bother with the flats on the shank, as long as your Chuck isn't a complete POS you shouldn't be spinning anything you can expect the motor to actually turn, least in a hand drill. May have a bit of a problem on the Bridgeport where you have more HP than the Chuck can hold, but from what I've gathered the holes you're tapping won't be up in the monster range so I don't imagine that'll be an issue

3 Phase Lightbulb
01-28-2019, 03:06 PM
I've always hand tapped and more often find I started the tap at just a slight angle making it very difficult causing a lot of back-outs and binding. I've always found it much easier to tap using a drill press, or the lathe, or the bridgeport to guide the tap but still manually turn the tap. I am looking forward to playing with a powered tapping head but admit I'm a little hesitant.

Dan_the_Chemist
01-28-2019, 03:20 PM
I am looking forward to playing with a powered tapping head but admit I'm a little hesitant.

Loan it to me and I'll return it in 6 months with a report. :)

BCRider
01-28-2019, 03:22 PM
I've always hand tapped and more often find I started the tap at just a slight angle making it very difficult causing a lot of back-outs and binding. I've always found it much easier to tap using a drill press, or the lathe, or the bridgeport to guide the tap but still manually turn the tap. I am looking forward to playing with a powered tapping head but admit I'm a little hesitant.

I really should make these someday but a simple block of steel with a few holes drilled to slip fit the more common sizes will ensure nice square starts. And it doesn't have to be very large. A 1" square block about 3/4inch tall could have at least four holes in it to accept #8, #10, 1/4 and 5/16 taps with a close but still slip fit with one hole in each corner. That way they'll fit in close to inside corners. Run the tap in for 3 or 4 turns then remove and finish without the block.

A slightly larger block for 3/8, 7/16 and so on and a slightly smaller one for #2, #3, #4 and #6 for the small stuff. I'd say a set of three and we'd have the straight starting guides needed for a pretty good variety of jobs from very small up to 1/2". Or the metric equivalents of course. These could be done in under an hour for all three if left with the mill scale on the blocks. Or a good afternoon and we'd have presentation grade tools to last our lifetimes.

I've tapped a lot of holes in my time and I always found that if I started them true to the hole that the job went well. Even for the small ones. I strongly suspect that there are two main reasons for taps snapped off in the work. One would be taps that are dull and bind and the other is taps started off center that dig into the sidewall of the hole far too deeply. A dirt simple guide is all that is needed to avoid at least one of these things.

BCRider
01-28-2019, 03:36 PM
Dan, you won't be using small taps on this. The scale of sizes you're working with even if you use screws every three inches suggests a size of 5/16... or 8mm if metric. And 3/8 would not be out of the question either. Threaded into aluminium and working with good brand name taps with spiral flutes and back relief ground into the thread forms you'd need to be pretty darned ham fisted to snap them off.

BUT, I would suggest that you still want some good and easy way to square up the taps so they run true into the holes. And that to me either means drilling the holes with some lead in as mentioned earlier and perhaps combining that with a ground pilot on the nose of the tap or using some manner of tapping guide. And again how will you be drilling all those holes in the first place? Those are a bit big to schlep up onto the mill or drill press. So odd are good that you would do well to make up a block jig that can clamp into position and then use drill bushings that fit into that jig. One sized to the tapping hole size then a second that would allow a half to one diameter of crest size relief and follow that down the same bushing with the tap to ensure a straight start. Move and re-clamp jig and repeat. Three drills set up with the tapping size drill and depth stop bushing over the drill on one, the clearance drill and depth stop on the second and the third with the tap. I'd also suggest an air nozzle with a long skinny tube to reach down and blow out the chips before each new operation.

Faced with the same job of drilling and tapping that many holes this would be my own approach just as described.

CPeter
01-28-2019, 03:39 PM
I do a lot of tapping with my mill/drill. It has a VFD. I use the speed control to start and stop the spindle. I run +/- 200 RPM for 1/4" and 5/16" taps. Really good control! I use the DRO to locate the holes, spot drill, drill all the holes and then come back and tap. Do all the same operation and then come back for the second and third. The DRO is a bottom feeder, but it will locate within a thou or two for the second and third operation. Very, very few broken taps and nice straight threaded holes.
CPeter

gellfex
01-28-2019, 04:12 PM
I do a lot of tapping with my mill/drill. It has a VFD. I use the speed control to start and stop the spindle. I run +/- 200 RPM for 1/4" and 5/16" taps. Really good control! I use the DRO to locate the holes, spot drill, drill all the holes and then come back and tap. Do all the same operation and then come back for the second and third. The DRO is a bottom feeder, but it will locate within a thou or two for the second and third operation. Very, very few broken taps and nice straight threaded holes.
CPeter

I have my Rockwell DP set up with a vfd too, and it taps very nice. I made a drill front control panel with a large STOP and a DPDT centering momentary toggle switch for 0N/direction, so it's easy to reverse, and the vfd takes care of soft deceleration/acceleration. If I had this job, I'd get a cheap little tabletop DP and mod it with a 1/2hp 3ph motor and vfd for tapping. Then just clamp it on this ginormous plate, rather than trying to set this plate up on a BP.

Freehand with a hand drill? Forget it, I've snapped off my share of 1/4-20 taps that way. It's hard to maintain the level of concentration required.

3 Phase Lightbulb
01-28-2019, 04:24 PM
These hand tappers work really well too if the item you're tapping is portable and small enough to place on one of these.

http://www.bbssystem.com/pictures/found.jpg

http://www.bbssystem.com/pictures/tapper.jpg

J Tiers
01-28-2019, 04:39 PM
A good bit of what he will want to do is into edges of bigger plates. I expect some will be into the face of thinner plates, where the combined drill/tap may help.

I'd not expect a lot to fit under there, but it depends on the throat depth... looks to be 3 to maybe 4 inches.

For general tapping, they certainly do work super. I have a different style, but same idea.

Arcane
01-28-2019, 04:41 PM
Dan, it might help generate more useful ideas if you told us what size holes you want and how they are spaced on your slab.

BCRider
01-28-2019, 04:42 PM
Those combined drill and taps are still only good for thru holes where the end of the drill breaks through before the threads engage. I'm pretty darned sure that they are not intended for thick and blind hole use. And I can only see lots of problems if they are forced into that sort of use.

3 Phase Lightbulb
01-28-2019, 04:46 PM
A good bit of what he will want to do is into edges of bigger plates. I expect some will be into the face of thinner plates, where the combined drill/tap may help.

I'd not expect a lot to fit under there, but it depends on the throat depth... looks to be 3 to maybe 4 inches.

For general tapping, they certainly do work super. I have a different style, but same idea.

The larger one above has a 7.5" throat depth: https://www.amazon.com/HHIP-3900-0250-Precision-Hand-Tapper/dp/B00QVYQR9W

The smaller one is height adjustable and actually has more clearance if needed.

J Tiers
01-28-2019, 04:50 PM
Those combined drill and taps are still only good for thru holes where the end of the drill breaks through before the threads engage. I'm pretty darned sure that they are not intended for thick and blind hole use. And I can only see lots of problems if they are forced into that sort of use.



..... I expect some will be into the face of thinner plates, where the combined drill/tap may help.

.....

Agree, won't be good for the big plates, but he's got a cross-gantry to do, and that I'd expect to use thinner plates. Maybe not, in which case it isn't gonna work for him. That's OK.

3 Phase Lightbulb
01-28-2019, 04:52 PM
Now this is kind of cool...

https://www.amazon.com/HHIP-3900-0254-Hand-Tapper-Magnetic/dp/B01BHHS9SO

https://images-na.ssl-images-amazon.com/images/I/718BEJstVrL._SL1500_.jpg

Noitoen
01-28-2019, 05:22 PM
Now this is kind of cool...

https://www.amazon.com/HHIP-3900-0254-Hand-Tapper-Magnetic/dp/B01BHHS9SO

https://images-na.ssl-images-amazon.com/images/I/718BEJstVrL._SL1500_.jpg
Is that a new type of magnet for aluminium? :cool:

754
01-28-2019, 06:11 PM
The crazy way, drill and then tap in one setup..turret mill. Easy
If you want 1 inch spacing easy 5 turns of handle, 2 inch spacing 10 turn am no DRO needed.
I think what many here may not realize, tapping heads have like 20 thou of float, so they still go straight if tap is 10 thou away from hole center .
I think 3phase , has a few tapping heads, rent one to Dan.
3 ph once you have used them, you will gladly install it on the machine if you have 20 holes or more.
I did thousands of holes with mine up to 1/2 coarse thread... sometime 200 threads per hour.,