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Flex arm alternative?

tjd10684

Cast Iron
Joined
Jan 26, 2011
Location
PA
So I got a job coming down the pipe to tap a bunch of holes in some 3/8" plate. Sizes range from m3-m5. The plates are around 25" sq and have ~75 holes in each that need tapped. The plates will be coming to me off the waterjet with undersized holes to be cleaned up with a drill bit.

I'm thinking this might be a perfect excuse to buy a flex arm (plan A) but since I'm not sure the bean counters will like that idea I'm working on a plan B. I have been searching around for some kind of drill attachment that will keep a tap nice and square to a hole but it a little more robust than say a simple tap guide. Something like that might work if it had maybe a mag base that could lock it in place nicely but the old finger clamps are not going cut it on this one.

Plan c is do clear off a second op machine and do it on there but for the size and weight of the plates and the small size of the taps I think its going to be a real pain probably in the back maybe the foot.

So any suggestions on a drill attachment or similar that might be able to help me out?
 

DDoug

Diamond
Joined
Oct 18, 2005
Location
NW Pa
So I got a job coming down the pipe to tap a bunch of holes in some 3/8" plate. Sizes range from m3-m5. The plates are around 25" sq and have ~75 holes in each that need tapped. The plates will be coming to me off the waterjet with undersized holes to be cleaned up with a drill bit.

I'm thinking this might be a perfect excuse to buy a flex arm (plan A) but since I'm not sure the bean counters will like that idea I'm working on a plan B. I have been searching around for some kind of drill attachment that will keep a tap nice and square to a hole but it a little more robust than say a simple tap guide. Something like that might work if it had maybe a mag base that could lock it in place nicely but the old finger clamps are not going cut it on this one.

Plan c is do clear off a second op machine and do it on there but for the size and weight of the plates and the small size of the taps I think its going to be a real pain probably in the back maybe the foot.

So any suggestions on a drill attachment or similar that might be able to help me out?

I think your going to need down pressure, and I have not seen a flexarm doo that.
A fosdick small radial drill would work well.

Have you thought about using a DRAP ?
 

gbent

Diamond
Joined
Mar 14, 2005
Location
Kansas
Perfect job for a old school gang drill press. Use tapmatic heads. You could make do with a standard drill press, just make an oversized sub table. Really cool would put a dot of stain at each hole when completed.
 

wgnrr1

Hot Rolled
Joined
Feb 14, 2008
Location
Spooner, WI
I agree with both above suggestions. A radial drill would be perfect, gang drill would be second choice.

Yes, both believed to be old/obsolete technology, but both could be had for far less cost than a flex arm. And both can serve several other purposes that the flex arm can't.

Sent from my rotary dial flip fone
 

atomarc

Diamond
Joined
Mar 16, 2009
Location
Eureka, CA
Will 3mm and 5mm (dinky) holes that are water jetted be capable of finish drilling without wandering and wobbling? I have no idea how perfect/accurately a water jet makes a small hole, but with such a small diameter, that water jetted hole better be dead nuts with no smegma on it or the dinky drill is going to do strange stuff.

I'll assume that the OP meant 3mm and 5mm for the water jetted hole

Stuart
 

Ray Behner

Diamond
Joined
Mar 27, 2009
Location
Brunswick Oh USA
Will 3mm and 5mm (dinky) holes that are water jetted be capable of finish drilling without wandering and wobbling? I have no idea how perfect/accurately a water jet makes a small hole, but with such a small diameter, that water jetted hole better be dead nuts with no smegma on it or the dinky drill is going to do strange stuff.

I'll assume that the OP meant 3mm and 5mm for the water jetted hole

Stuart

Yep, sounds like a pain in the butt. Do you have a datum to start from, or you gotta find each hole from the unknown?
 

newtonsapple

Cast Iron
Joined
May 16, 2017
Here is a really good alternative:


Definitely look at farming them out. Cut the profile on the waterjet. Drill and tap all the holes on the mill. In that size, chasing a waterjet hole isn't saving anything and you eliminate all the piercing time on the waterjet.
 

kb0thn

Hot Rolled
Joined
May 15, 2008
Location
Winona, MN, USA
We got the cheapest possible eBay pneumatic tapping arm a few years ago. Less than $500. It works fine tapping #4 up to 3/8". We do some 3/8"-16 and 3/8"-24 in 3/8" plate.

The quick change collets that were included with the machine use ISO sized tap shanks, I think. Which isn't what we have here. So I've had to buy US sized collets at $100 a piece. But they are off the shelf and in stock at MSC.

The machine uses a lot of air and makes a lot of noise. We only run maybe 1k to 5k holes per month. But I plan to replace the arm with a electric tapping arm. They have some Chinese servo drive arms that look to be a quieter alternative.

We laser holes on size and tap directly. No thread specs to meet. Just functional threads for attaching covers and brackets and what-not.
 

Orange Tapper

Plastic
Joined
Apr 27, 2021
Another option is one of these.

Tap holder.jpg

It holds a quick change tap holder one end and is a standard Morse taper the other, only thing is you would have to stop and switch to reverse once you've tapped to the desired depth, which can be a pain if you've got a lot to do. But will reduce the chance of breaking a tap and will keep the tap straight.

other than that a Tapmatic head as already mentioned would work much better and quicker.

But if you can get a Flexarm or something similar they are the bee's knees so to speak. especially as you don't have to move your part around to each hole as you do with the quick change tap holder or a Tapmatic head. We've got a tapping arm from a company called Ragnar Machinery which is great, it's got a control that lets you program your tap pitch and desired depth, then it's as simple as lining up over the hole and pressing go and the arm will tap the hole to depth and retract back out. Well worth it if you do a lot of tapping.

Will
 








 
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