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loose nut
12-26-2008, 06:33 PM
My nephew has a job coming up that requires 15,000 identical parts with a tapped hole, under 1/2" I believe, and needs some type of equipment to speed up the tapping of the holes.

There are various types of tapping heads available that can be put into a drill press , is there one type or brand that is better then the others or that works better. I have heard that they may not be dependable and won't hold up to constant work load?????

Is there any other way to do this type of job with some other piece of equipment, I don't believe the profit margin will allow the purchase of any type of dedicated tapping machine.

Jpfalt
12-26-2008, 06:40 PM
My usual method is to grab the tap in a drill chuck or collet, run the speed down and use the reversing switch.

I use a Bridgeport with a back gear and using a keyless chuck, I put i sequence:

center drill with back gear off
tap drill with back gear off
tap with back gear on.

Using the reversing switch, you tap to depth and then reverse the tap out of the hole. This works best with a spiral point or gun tap.

I also set up my drill press with a reversing switch. It's single phase, so I have to allow for coast down to a stop before reversing.

Mark McGrath
12-26-2008, 06:56 PM
At 15,000 holes he does not want to be considering a Bridgeport or any other machine that has to run slow and be switched manually from forward to reverse.
Depending on the shape and size of the part he needs a tapping attachment for a drill at the very least.
The type that have forward reverse clutches built in to them.
15,000 holes is not a really huge quantity.For many years on one job alone I tapped 40,000 M10 holes every week.

teejay
12-26-2008, 07:23 PM
Look at the Tapmatic self reversing tap heads they work in a drill press.We use them on an old Burgmaster indexing drill press.

oldtiffie
12-26-2008, 08:08 PM
Is this "tapping" job into a "flat" or into a "round"? Is that "under 1/2" the depth of the hole or the size of the tap? Is the hole "blind" or "straight through"?

If it were me I"d have priced in having it "farmed out" to a "specialist" firm. Their costs are so low compared to yours that it may well be that you'd make more money that way than doing it yourself. The risk of non-specialised tools/machines breaking down or mal-functioning is too high.



At 15,000 holes he does not want to be considering a Bridgeport or any other machine that has to run slow and be switched manually from forward to reverse.
Depending on the shape and size of the part he needs a tapping attachment for a drill at the very least.
The type that have forward reverse clutches built in to them.
15,000 holes is not a really huge quantity.For many years on one job alone I tapped 40,000 M10 holes every week.

Mark, if my math is OK and if you were working 40 hours a week, that is 1,000 (drilled and?) tapped holes per hour which is 3,600 seconds/1,000 parts = 3.6 seconds per part. If that was spread over several machines or over longer than 40 hours per week, it would be a strain but "do-able". It would not need too many "hiccups" along the way to bring things to their knees.

These are a couple of the tapping heads available here in OZ:
https://www.machineryhouse.com.au/Products?stockCode=T003

https://www.machineryhouse.com.au/Tapping-Chucks-Reversible

Lets say that the cost for the tapping head to be amortised over the job was US$300. That is $300/15,000 = $0.02 per tapped hole just for the tapping head alone.

I amortised it over the one job as there was no indication of any further "paying" jobs for it.

The material, the type of taps and the power/speed of the mill/drill etc. as well as "replacements" and "availability" of drills and taps and use of tapping lubricant etc. etc. are critical as well.

If this is "manual" instead of "mechanised/automated", someone is going to get as frustrated as hell and bored $hit-less - or perhaps I should say that if it were me, that's how I'd re-act.

Mark Hockett
12-26-2008, 09:32 PM
If you want a production tapping head Procunier is the best.
http://www1.mscdirect.com/CGI/NNSRIT?PMPXNO=1801732&PMT4NO=55696192

I doubt a Tapmatic head would make it through 15,000 parts without breaking, they are light duty when compared to a Procunier.

Herm Williams
12-26-2008, 11:07 PM
I did a similar job a few years ago. iirc if cost almost a thousand dollars to get started. I used two Delta 3/4 hp drill preses mounted on a table, a step drill to drill and break the hole edge, a procunier tapping head mist spray lub. 1/2 13 tap, 1 inch deep thru hole. drill fixture to hold the item while being drilled and another while tapping. cast alum material. A job like that rates close to watching crab grass grow after a few hundred.
re

loose nut
12-27-2008, 09:33 AM
If it were me I"d have priced in having it "farmed out" to a "specialist" firm. Their costs are so low compared to yours that it may well be that you'd make more money that way than doing it yourself. The risk of non-specialised tools/machines breaking down or mal-functioning is too high.


.

They did, that's how he got the job.

It's something he picked up to do over the winter (hence the budget constraints) when he can't do his regular work because of the weather. He did 15,000 already, and has another batch coming with the possability of 50,000 next winter, it's not that he can't do it in time, he is just looking at speeding things up.

The material is flat aluminum, thread size, I didn't ask but not to big.

It may be boring but it keeps them eating.

DR
12-27-2008, 02:14 PM
...............................

I doubt a Tapmatic head would make it through 15,000 parts without breaking, they are light duty when compared to a Procunier.

I agree.

Tapmatics are highly promoted with full page ads in the trade mags.

Unfortunately, that doesn't make them good.

Go to any large shop auction and you'll very likely see a box full of broken Tapmatic heads.

gellfex
12-27-2008, 04:24 PM
My usual method is to grab the tap in a drill chuck or collet, run the speed down and use the reversing switch.

I use a Bridgeport with a back gear and using a keyless chuck, I put i sequence:

center drill with back gear off
tap drill with back gear off
tap with back gear on.

Using the reversing switch, you tap to depth and then reverse the tap out of the hole. This works best with a spiral point or gun tap.

I also set up my drill press with a reversing switch. It's single phase, so I have to allow for coast down to a stop before reversing.

I have a Ettco tapping head I picked up at auction years ago for $35, but I sometimes now prefer to use the reversing of my VFD equipped drill press. You can reverse it running and it's does a sweet controlled decel and reverse. As a bonus you get to dial exactly the speed you want. What I need to make is a tap holder with a hex shank so I don't have trouble with the keyless chuck being too loose to grab the tap.

This kind of job depends on deciding precisely what % of thread you need for the piece and knowing when to pitch the dull tap. A 75% thread will make it a lot tougher than a 60% that might be just fine for the job. I rarely tap steel higher than 60%.

oldtiffie
12-27-2008, 04:35 PM
Originally Posted by oldtiffie
If it were me I"d have priced in having it "farmed out" to a "specialist" firm. Their costs are so low compared to yours that it may well be that you'd make more money that way than doing it yourself. The risk of non-specialised tools/machines breaking down or mal-functioning is too high.


They did, that's how he got the job.

It's something he picked up to do over the winter (hence the budget constraints) when he can't do his regular work because of the weather. He did 15,000 already, and has another batch coming with the possability of 50,000 next winter, it's not that he can't do it in time, he is just looking at speeding things up.

The material is flat aluminum, thread size, I didn't ask but not to big.

It may be boring but it keeps them eating.

Thanks loose nut.

I am glad its working out that well.

I took it from the OP that this was a "first time" effort. But as he has done it before, did as well as he did, and is having another go at it and that its worthwhile, it has to be the best of all worlds.

Mark McGrath
12-27-2008, 05:13 PM
Quote
"Mark, if my math is OK and if you were working 40 hours a week, that is 1,000 (drilled and?) tapped holes per hour which is 3,600 seconds/1,000 parts = 3.6 seconds per part. If that was spread over several machines or over longer than 40 hours per week, it would be a strain but "do-able". It would not need too many "hiccups" along the way to bring things to their knees."

Originally it was done as the part was machined on a multispindle lathe.The machine made 360 parts an hour and ran up to twelve hours a day.Out of that twelve hours there was down time for bar stocking and tool changing although we ran carbides with strict schedules on tool changing which at worst was the part off tip which got changed every thousand parts.Quantities were upped to 40,000 which meant putting another machine on the job and after a disaster where a tap had gone and we had a bin of thousands of parts some of which had faulty threads the decision was taken to build a dedicated machine to tap them and this did fourteen parts per minute.
To someone who has never worked with multispindle autos the numbers are a bit mind boggling but believe me they are true.
We had other machines running parts in the region of 12,000/week with M10 x 23mm deep threaded holes.
We did an angle bracket measuring 250 x 102 with a 36mm turn out of 4mm plate at the rate of 10,000/week.Each bracket needed 1kg of material.
We had 100`s of jobs like that for one customer.All gone now as the volume work has moved offshore.
A large volume for us now is 5,000 parts/week.Good thing about these is they used to be made in Singapore and delivered to Scotland.Now they are made in Scotland and end up all over the world.

John Stevenson
12-27-2008, 05:47 PM
What about a stand alone air tapper ?

Free's up normal machines, fast, if you have it bench mounted you can use it for anything. Even doing just two holes is quicker that getting the tap wrench out.

http://homepage.ntlworld.com/stevenson.engineers/lsteve/files/tapping1.jpg

I bought the head and collet set and made the rest out of 40mm square box section. Took me a full day to make the frame but it's better than the bought ones and does exactly what I want.

http://homepage.ntlworld.com/stevenson.engineers/lsteve/files/tapping3.jpg

It's been painted since then and looks quite nice now, folds away when not in use.

In hindsight I should have bought one / made one years ago.

.

Mark McGrath
12-27-2008, 05:58 PM
Tapping arms are good and fast for a job shop but I`ve never found them a lot of use in higher production quantities and compressed air is expensive.I prefer Herbert Flashtaps for medium volumes,Herbert drills with tapping for a few here and a few there,and for the high volumes build Shrader tapping and drilling heads onto indexing tables.
At the end of the day I`ve always found the deciding factor to be the shape of the part.Can you hold it in your hand,can it drop into a loose fixture or is it cylindrical and needs clamped.

oldtiffie
12-27-2008, 11:19 PM
Mark,
you have made my point precisely as regards the differences between the average HSM and "jobbing" shops on the one hand and specialised high-volume shops on the other.

Thanks for that.

John and Mark,
can you please post the details of those air-tappers as I'd like to have a look into them.

Mark McGrath
12-28-2008, 05:52 AM
I`ll leave John to explain the articulated arm tappers to you as he uses them and has built one.
Anyone know how a multispindle lathe taps?
A clue.The spindles and tap only run in one direction and never stop.There are no forward reverse clutches either.

Peter.
12-28-2008, 06:34 AM
I can only imagine that the tap collapses for withdrawing at a pre-determined depth. Can't think how that would be achieved with smaller taps though.

Ian B
12-28-2008, 06:44 AM
Mark,

The spindle spins at such a speed that the tap is plucked from its collet and fired through the spindle bore. At this point, it is caught in a net by a tap elf, who dutifully reloads it into the magazine on the lathe's tailstock.

Or something like that.

Ian

oldtiffie
12-28-2008, 06:51 AM
My guess is that either the part speeds up relative to the tap or the tap slows down relative to the part. In either case the tap will be withdrawn ready for the next cycle. The tap is not loosened in its "chuck".

Mark McGrath
12-28-2008, 07:14 AM
Tiffie,
a bit of explanation here.
http://www.practicalmachinist.com/vb/showthread.php?t=167693

oldtiffie
12-28-2008, 07:40 AM
Thanks Mark.

Rustybolt
12-28-2008, 10:44 AM
A 'Snow' tapping machine would be ideal, but we don't live in an ideal world so,. I've used 'Procunier' tapping heads with good results in both drill presses and milling machines. However, in a lot of cases it's how the part is fixtured that can speed up or slow down the process. I could tell you more if I knew what the part looked like. Lotsa lube.
Try googling -Schrader-Bellows hydracheck unit. These were drillpress attachments that made drilling and tapping a lot easier. They were air over oil.