Gunsmithing Tapping 1/2" UNF Action truing jig. Help

[irlightbuilds]

I have got the point where I have my 12 holes drilled in my action truing jig and I am ready to tap the holes.

I have recessed a faceplate to accept the 316 stainless steel tube. I intend to weld the tube to the faceplate.

The tube has a 3/4" wall thickness.

I would be very grateful for any info on the best type of taps to buy to tap this type of stainless steel.
I only have an HSS 1/2" UNF taper tap right now, I suspect this might be only good for starting the thread off, then go on to a plug tap.

What type of tap set should I purchase to make this job easier. Is HSS good enough to do the job with plenty tap fluid. Or should I be buying a tougher type tap set.

I have a large pedestal drill that I can use to help centre the tap. Or I can weld the tube to the faceplate and hand tap whilst fitted to the spindle.

Open to suggestions please.

I intend to heat the faceplate before welding with my Mig welder using normal mild steel wire. If this is not a good idea, please inform which is the best way to proceed.

Cheers

 

[hero's machine]

Re: Tapping 1/2" UNF Action truing jig. Help

A lot will depend on how your drilling operation went. I tap in the same setup and start my tap under a spring loaded center, it makes it easy to start square. I taper tap is perfect for the through hole. If your tap shows sign of resisting.....stop. find a sharp tap. If it still resists, you may have work hardened the hole while drilling and carbide may be your answer.

I have welded stainless with 7018 with success, although it lacks strength and visual quality. I would buy a pound of stainless rod and be done.

 

[irlightbuilds]

Re: Tapping 1/2" UNF Action truing jig. Help

The tube drilled very easy with a 29/64 MT 1 new drill.
I lubricated all the way through the drilling process on each hole.
I was surprised how easy it drilled. I have read horror stories regarding working with stainless.

I got my hands on two blocks of stainless steel that are 5" long x 2 1/2" square. I am making a barrel vice with them.
I have drilled the two main holes that will have 0.787" threaded rod (20mm). I have to tap the bottom block to screw the threaded rod into and then oversize drill the top block.
Looking at recessing the two bars, so that I can fit two compression springs to keep the two bars apart.
Thank you for your reply.

 

[ukshooter]

Re: Tapping 1/2" UNF Action truing jig. Help

Good luck with the jig.
I'm a little puzzled about your choices.
I can work in both imperial and metric.
Why make this with imperial bolts when they cost a fortune and are hard to find in the UK.
Surely M12 bolts and taps would be cheaper?.
I have broke a few taps in my life time and main reason were :-

Cheap taps/second hand taps no good-Buy new and buy the best you can afford.

Wrong size hole/if you haven't got the correct size drill,don't use the nearest smallest size you have got.

Stainless steel is bastard to thread/use a stainless anti galling cutting compound.Plus can use it when fitting barrels.

Take your time don't rush the job,sounds like your going to hand tap these on a drill press.
THREADING WITH DRLL PRESS
You start with a taper tap/pointy one.
Then a intermediate tap/less pointy one.
Finish plug tap/this ones parallel.
threading pdf

No need to heat before Mig welding,if jobs worth doing do it right get some stainless Mig wire.

 

[irlightbuilds]

Re: Tapping 1/2" UNF Action truing jig. Help

Well guys. I took the plunge and went out to my workshop and tapped three holes using a good oil.
I have to say it was not hard. The tap cut with a 3/4 turn forward then back 1/4 turn.

UK Shooter. I intended to use the tap to also cut threads for thread protector taps. Hence using the 1/2" UNF taps.
I am 49 years old, I went through the transition from imperial to Metric. I still measure in feet and inches and weigh in pounds and stones

I only have the Mig welder. to use Stainless wire would I not have to use pure argon gas. I use Argo shield heavy. I get it at £30 for a full size bottle.
As for the heating of the faceplate. I was under the opinion that when welding cast steel you have to heat it before welding.

I appreciate the input from you guys.

 

[ukshooter]

Re: Tapping 1/2" UNF Action truing jig. Help

I assumed the base plate was stainless steel.
You need to provide more details. Casting is the method used to shape the metal so it could be mild steel, low alloy or even stainless.
Just be careful,I'd be tempted to practice on spare material.
WELDING CAST STEEL

 

[irlightbuilds]

Re: Tapping 1/2" UNF Action truing jig. Help

UkShooter. I should have said cast iron.
When I was turning the diameter of the faceplate, it did not cut like steel, i.e like strands of steel spiralling from the cutting face.
It was a black almost like a thick powder consistency., or maybe like granulated brown sugar consistency.
It got every where and was a bugger to clean up.
I have seen threads on this or maybe another forum where it is mentioned that the cast iron has to be heated before welding. Then left to cool over time.
I do not have anything like this metal to practise welding on.

It would have been good if it was Stainless. I would have purchased some Stainless welding rods and used my friends Arc welder to weld the two together.

 

[hero's machine]

Re: Tapping 1/2" UNF Action truing jig. Help

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TikkaM55sporter</div><div class="ubbcode-body">UkShooter. I should have said cast iron.
When I was turning the diameter of the faceplate, it did not cut like steel, i.e like strands of steel spiralling from the cutting face.
It was a black almost like a thick powder consistency., or maybe like granulated brown sugar consistency.
It got every where and was a bugger to clean up.
I have seen threads on this or maybe another forum where it is mentioned that the cast iron has to be heated before welding. Then left to cool over time.
I do not have anything like this metal to practise welding on.

It would have been good if it was Stainless. I would have purchased some Stainless welding rods and used my friends Arc welder to weld the two together.
</div></div>

Test it with a magnet.

If it is cast, machine a groove for the tube to sit in, use 7018 to weld it up. You can preheat, but not totally necessary......IF you skip weld it with small stringers. Keep them an inch or less. Work it like if you were changing a tire. Peen the snort out of it as it cools (wear safety glasses, slags gonna fly). Don't get greedy and peen it....you'll be fine.

 

[671RTO9513]

Re: Tapping 1/2" UNF Action truing jig. Help

Tikka

When I tap holes such as you've done on a jig like this, I do it right after drilling (assuming you have a rigid workpiece setup).
With a through hole, use a spiral point tap, sometimes called forward chip drive and just slow the machine some and run it through (with good cutting fluid of course). Keeps everything in line and is much quicker. That 1/2 NF is an easy tap to drive.

The spiral point tap does not require you to back it up like a hand tap, so it's fine to use it with power.

 

[irlightbuilds]

Re: Tapping 1/2" UNF Action truing jig. Help


<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 671RTO9513</div><div class="ubbcode-body">Tikka

When I tap holes such as you've done on a jig like this, I do it right after drilling (assuming you have a rigid workpiece setup).
With a through hole, use a spiral point tap, sometimes called forward chip drive and just slow the machine some and run it through (with good cutting fluid of course). Keeps everything in line and is much quicker. That 1/2 NF is an easy tap to drive.

The spiral point tap does not require you to back it up like a hand tap, so it's fine to use it with power. </div></div>

I like your set up for using spiral taps. They sound just the job. Unfortunately my drill vice is not wide enough to take the tube and tighten it up to give rigidity. I will have to cure that problem and get a wider vice.

Having read your post I can see where I can improve my tapping skills.
I am looking at buying a Mill, which would be much better than the drill press. With a bigger vice to boot.

The tap I am using is a 4 flute which was brand new. I had to give up last night on the third hole as the tap wrench I was using was a cheap piece of §h±t. The V in the wrench where the tap sits was made from Aluminium and it was just a straight bottomed threaded rod that secured the opposite side of the tap. I am looking this morning at a better quality tap wrench online.

I live way up in the hills of the Scottish Borders, I have to normally buy my tools online, then have to wait for them to be delivered, which is a pain in the butt. Something we have to put up with living where their is no street lighting and no passing cars. Only noise is sheep and the odd passing aeroplane. We are lucky to live here.
Thanks to all for taking the time to post replies

 

[irlightbuilds]

Re: Tapping 1/2" UNF Action truing jig. Help

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: hero's machine</div><div class="ubbcode-body">[

Test it with a magnet.

If it is cast, machine a groove for the tube to sit in, use 7018 to weld it up. You can preheat, but not totally necessary......IF you skip weld it with small stringers. Keep them an inch or less. Work it like if you were changing a tire. Peen the snort out of it as it cools (wear safety glasses, slags gonna fly). Don't get greedy and peen it....you'll be fine. </div></div>

I tested the D1-4 Back plate with a magnet and it did stick to the back plate.
I know the script regarding welding. I never start from point A and weld all the way around.
I tack the workpiece first then weld opposite sides till the four sides are done.

 

[irlightbuilds]

Re: Tapping 1/2" UNF Action truing jig. Help

All 12 holes are now tapped. It must be a good quality HSS tap, as it tapped the last hole with the same effort as the first.
I reckon I will take the back plate and Jig to the local welder and have them weld it with the correct Nickel rods.
I am also converting another D1-4 back plate to a spider with a welded on piece of Stainless tube, to fit to the spindle for shorter barrel threading. should gain a couple of inches.

 

[hero's machine]

Re: Tapping 1/2" UNF Action truing jig. Help

You don't HAVE to use ni rod. If you stitch it up with small stitches it will be fine. I have welded about every cousin of steel with good success using 7018 or 309. The part that I would worry about is the brittlness of the cast at the HAZ and the leverage available at the end of your jig. Given the fact that you have 3/4" wall thickness, I would machine a groove to recess the pipe into then set it with some 3/8" or similar bolts from the back side and then you don't sweat changing dimensions on your back,plate. Every time you heat it or weld it, you run the risk of changing its dimensions.

If you choose to weld it, keep stringers small and short....1/2" would be a good length to strive for. You can't omit peening....every single stringer needs to be peened.