Agree with all of that. - dan
Drill + tap failure. Backwoods Outdoors Corbeil Ontario.
- Thread starter Jimbobob08
- Start date
Agree with all of that. - dan
David Henry
CGN Regular
- Location
- West of the big road
I'd say the fellow that did the job needs to know how to grind a bottoming tap. These holes are started with a standard taper tap and left at that. I would follow up with a plug tap then a bottoming tap. That should fix the problem with no need for lock tite. The rifle is not a wreck but the job is only half done. D.H.
mmcintyre1220
CGN frequent flyer
- Location
- Tillsonburg, Ontario
Good Lord..... I am by no means a machinist (went to school for welding and then onto powerline tech) but dam, I have drilled and tapped a few receivers now and have never had one of them fail on me.
Falconflyer
CGN Ultra frequent flyer
My goodness what a mess! Let's hope they fix it properly and if not then they owe you a new gun in my opinion!
Jonnyofalltrades
Regular
- Location
- North-central Saskatchewan
I'm astounded that they would charge money for work like that. The holes do look straight, on a positive note. Should make it easier to bump up to 8-40.
(Usually have to straighten out crooked holes when doing that.)
(Usually have to straighten out crooked holes when doing that.)
Take guntech's advice and quit beating yourself up.
Those holes are definitely oversize but they can be ''fixed'' to work well enough.
That mess in front of the rear sight dovetail looks like someone tried to epoxy the base in place.
If they actually told you they didn't have a bottoming tap, that pretty much would sum up my opinion of that smith.
It takes all of ten minutes at most, even for the most incompetent smith to grind down a tap to cut threads to the bottom of a hole.
Make sure they refund you money and charge them for the gas.
Those holes are definitely oversize but they can be ''fixed'' to work well enough.
That mess in front of the rear sight dovetail looks like someone tried to epoxy the base in place.
If they actually told you they didn't have a bottoming tap, that pretty much would sum up my opinion of that smith.
It takes all of ten minutes at most, even for the most incompetent smith to grind down a tap to cut threads to the bottom of a hole.
Make sure they refund you money and charge them for the gas.
It's not too late. It can be fixed.
You can install helicoils in those blind holes and get some decent thread engagement. But that whole setup is a little sketchy.
A helicoil will be just as strong as a regular thread in steel if done correctly.
You can install helicoils in those blind holes and get some decent thread engagement. But that whole setup is a little sketchy.
A helicoil will be just as strong as a regular thread in steel if done correctly.
- Location
- Western Manitoba
Is a curious thing to see - like 35 years ago we got "new" machinists at the mine - they earned nickname as the "loctite twins" - was their view that loctite would handle up to .004" gap, so was as accurate as their machining needed to be - we were supposed to get used to use loctite, instead of parts that fit. Was very different approach from former "old guy" - or at least old guy was smart enough not to say anything about it - but since we were installing bearing races on rotor shafts - could most definitely tell when a race needed to be induction heated to get that race to fit snugly to a "built up and re-machined" shaft.
Through my own klutziness, though, I made similar discovery as OP did - on a new - bought in 2013 - Zastava Model 70 - that front sight ramp - not really held on there with anything except a "glue" of some sort - when you slide over the front sight insert, you see a screw head underneath - I had thought that was threaded into the barrel - nope - it threads into a cylinder that is set into a very shallow dovetail that was milled on that barrel - the front sight ramp slides down over top of that cylinder - so removing that screw is not enough to remove that front sight ramp - still have to overcome that glue - which I managed to do by trying to tap out that factory front sight with inadequate support to the ramp - managed to knock the entire thing off the barrel and discovered how it was mounted there. I suspect there are modern "glues" no doubt as strong as old time lead/tin soft solder - might be able to be used in place of - but is likely places where neither are the appropriate way to fasten two things together - depends on the expected service, I guess.
Through my own klutziness, though, I made similar discovery as OP did - on a new - bought in 2013 - Zastava Model 70 - that front sight ramp - not really held on there with anything except a "glue" of some sort - when you slide over the front sight insert, you see a screw head underneath - I had thought that was threaded into the barrel - nope - it threads into a cylinder that is set into a very shallow dovetail that was milled on that barrel - the front sight ramp slides down over top of that cylinder - so removing that screw is not enough to remove that front sight ramp - still have to overcome that glue - which I managed to do by trying to tap out that factory front sight with inadequate support to the ramp - managed to knock the entire thing off the barrel and discovered how it was mounted there. I suspect there are modern "glues" no doubt as strong as old time lead/tin soft solder - might be able to be used in place of - but is likely places where neither are the appropriate way to fasten two things together - depends on the expected service, I guess.
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My iron would for sure not be returning to that establishmint.
Full refund and iff'in the cost is more to fix it than they charged you, they should be worthy of that expense as well.
Ohhh leee fruck.
Friday thuh 13th lawng weekend jawb.
Full refund and iff'in the cost is more to fix it than they charged you, they should be worthy of that expense as well.
Ohhh leee fruck.
Friday thuh 13th lawng weekend jawb.
Hmmm... Part of the issue may be the base. It appears to be sitting proud of the barrel, perhaps the radius is wrong. This would create a host of issues - screws being too short, bending moment being applied to exposed screw shank. etc.
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Just to update everyone and clarify. The business is a small shop, father and son. Usually talk to son, he’s the one that answered yesterday that said just drop the rifle off for repair, father does all the work. This is the first time dealing with them. There was a lack of understanding and communication between the two. So I emailed them this morning with all the pictures, and expressed the issue fully, and what was discovered when the drill and tap failed. I expressed my concern of just dropping the rifle off, and what the repair would be, including the damage from the epoxy used on the skinner rail and barrel. I did mention this thread since I believe they’re a member here, but am not sure how active. Maybe they’ll login and see what people think a remedy could be to this issue.
You are correct that it is the barrel that’s drilled. I believe I have the only era (earliest) Rossi 92 that isn’t drilled there from the factory. How deep the factory drills, and how far my rifle was drilled is something I may dig deeper into.
Jonnyofalltrades
Regular
- Location
- North-central Saskatchewan
Drilling and tapping a blind hole in a barrel is touchy enough of a job already. Helicoils are great, but not here.
Helicoil doesn't make 6x48 inserts, that I can find.
- Location
- Western Manitoba
How deep? - was mentioned in Post #19 - is various tables / references available - what size of hole, where on the barrel (chamber? muzzle?), how deep to go (% of barrel wall or minimum amount to be left from the bore /rifling). From what I have seen, I think some engineers can work that out using "hoop stress" calculations - more than likely was worked out by tradesmen trial and error over decades of just doing it and having it fail or not. But, for example, you can go with less barrel thickness left using a #6-48 tap drill (#31 drill - 0.1200" diameter), versus using an #8-40 tap drill (#28 - 0.1405" diameter), and makes difference if you are over the chamber, or near the muzzle. Some machinists use other size bits to get different "thread fill". Also the hole itself - is bottom end of it a "V" like from a standard drill bit, or is it flat - like from a re-ground drill bit? So advice to simply re-drill hole to larger size, puts you at different place on that table - what was acceptable with a small hole, might not be so, with a larger diameter hole.
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fingers284
CGN Ultra frequent flyer
- Location
- Alberta Cowboy Ranges
No doubt the screw threads/holes are a mess of monumental poor work but the first mistake made was deciding to match a rail with a barrel track that is the same dia from front to back on a tapered barrel....one or the other has to be modifies to mesh together. It appears that they tried to "bush" the different radi with a liberal gumming up with filler locktite. There is a locktight product that is designed for shoring up loose shafting to a pully or gear but this sure aint the place to use the stuff.
I had this photo file in the computer.
This is a Williams "Shorty" ramp I installed on a M94 Winchester carbine barrel. One screw. You get one chance to do this right. As mentioned above, making the hole flat bottomed gives a bit more usable depth. A sharp properly ground bottoming tap is required to get the maximum number of usable threads. 48 pitch threads take about 21 thou. per thread. To be effective, you are going to need something over a sixteenth of an inch of perfect full threads to get decent engagement with the screw. And the length of the screw has to be optimized to get that engagement.
Drilling and tapping blind holes in a barrel leaves little room for error.
If you have a look at sight holes drilled and tapped for front and rear sights in something like a M700 Remington, you can get an idea of how these holes are handled by a factory. You can calculate the barrel wall thickness, then measure the depth of the hole, to get an idea of how much barrel wall manufacturers leave.
This is a Williams "Shorty" ramp I installed on a M94 Winchester carbine barrel. One screw. You get one chance to do this right. As mentioned above, making the hole flat bottomed gives a bit more usable depth. A sharp properly ground bottoming tap is required to get the maximum number of usable threads. 48 pitch threads take about 21 thou. per thread. To be effective, you are going to need something over a sixteenth of an inch of perfect full threads to get decent engagement with the screw. And the length of the screw has to be optimized to get that engagement.
Drilling and tapping blind holes in a barrel leaves little room for error.
If you have a look at sight holes drilled and tapped for front and rear sights in something like a M700 Remington, you can get an idea of how these holes are handled by a factory. You can calculate the barrel wall thickness, then measure the depth of the hole, to get an idea of how much barrel wall manufacturers leave.
