GTA
All Springer/NP/PCP Air Gun Discussion General => "Bob and Lloyds Workshop" => Topic started by: mackeral5 on January 02, 2020, 10:39:51 AM
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I am interested in purchasing tooling to assist me in creating/modifying .30 barrel chambers. I found this kit at Pacific tool.
http://pacifictoolandgauge.com/throat-and-neck-reamers/5266-17-cal-uni-neck-and-throater-kit.html#/1209-specify_reamer_caliber-30_cal_300_cal_308_cal_762mm_782mm (http://pacifictoolandgauge.com/throat-and-neck-reamers/5266-17-cal-uni-neck-and-throater-kit.html#/1209-specify_reamer_caliber-30_cal_300_cal_308_cal_762mm_782mm)
The kit is customizable for neck diameter, which I believe translates to chamber diameter.
I hope to be able to use the same kit for .30 and .308 barrels, assuming this is possible.
What neck/chamber diameter should I specify ?
If there is a better path to take here, please let me know. My goal is to be able to create .30 and .308 chambers/leads in raw blanks and adjust existing chambers/leads, using a system such as this that does not require machine tools.
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I am interested in purchasing tooling to assist me in creating/modifying .30 barrel chambers. I found this kit at Pacific tool.
http://pacifictoolandgauge.com/throat-and-neck-reamers/5266-17-cal-uni-neck-and-throater-kit.html#/1209-specify_reamer_caliber-30_cal_300_cal_308_cal_762mm_782mm (http://pacifictoolandgauge.com/throat-and-neck-reamers/5266-17-cal-uni-neck-and-throater-kit.html#/1209-specify_reamer_caliber-30_cal_300_cal_308_cal_762mm_782mm)
The kit is customizable for neck diameter, which I believe translates to chamber diameter.
I hope to be able to use the same kit for .30 and .308 barrels, assuming this is possible.
What neck/chamber diameter should I specify ?
If there is a better path to take here, please let me know. My goal is to be able to create .30 and .308 chambers/leads in raw blanks and adjust existing chambers/leads, using a system such as this that does not require machine tools.
Wondering abpout such a tool myself. I was thinking I saw someone here who makes custom reamers. I might be interested one for a .458 if my back woods bubba tools don't work.
Looking at it further I dont think this is adjustable for .300 bore. It is adjustable for freebore depth. Youd have to order one for .300 if they make it.
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The reamer is not adjustable for diameter, it must be made for whatever chamber diameter you require.... A .300 cal airgun barrel will require a smaller reamer than a .308 cal PB barrel....
I don't know if these reamers cut a tapered leade on the rifling at the same time as they machine the chamber or not.... Your best bet would be to contact the company and describe what you need.... When making my own chamber reamers, I use a tapered leade angle of 1 deg. per side, ending in a parallel chamber 0.001-0.002" larger than the groove diameter of the barrel.... They have a pilot that is 0.002" smaller than the land diameter to guide them straight into the bore....
(https://i378.photobucket.com/albums/oo221/rsterne/6mm%20Sporter/Tempered%20Reamer_zps2bub7oat.jpg) (http://s378.photobucket.com/user/rsterne/media/6mm%20Sporter/Tempered%20Reamer_zps2bub7oat.jpg.html)
and before you ask, I don't make them for others, sorry....
Bob
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Thank you for the replies. As I understand it the throat cutting portion cuts a 30 degree lead on the rifling. I did end up sending Pacific tools an email, I will share info once I hear back from them.
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A 30 deg. leade angle will require that you cut the chamber to precisely the correct length for a given slug.... Too shallow it won't chamber without excessive force, and too deep the slug will get a running start before it hits the lands.... If you are chambering the barrel for pellets, this is much less critical....
Bob
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Unfortunately it appears the Premium Uni-Throater / Necker Kit besides being expensive, is designed for use in powder burning, necked cartridge chambers. From what I read in the description, there is a 'dummy' chamber that goes into the barrel that is already chambered for a given cartridge, then you can adjust the free-bore or the lead-in area in front of the chamber for a given bullet. I do not believe it will work for airgun applications, you'd be better off bribe'n Bob with the similar amount of cash as Pacific Tool & Gauge wants. ;)
M
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Understood..... I will call them and ask of they have a product to offer for airgun chamber/lead purposes.
The price may seem high, but if it performs as designed the value is there, IMO.
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Hopefully you will post what you find out from PT&G about airgun chamber reamers, I am sure they will cut anything you wish for a price. I would like to know since I am staring down the barrel of a chambering project myself and not looking forward to making and heat treating my own reamers. I am sure it is no big deal, but I am betting the first one is the toughest with lots of errors along the way. I may just cut them and pay a knife maker friend to do the heat treating for me since he has the proper oven and knowledge to do it.
Nothing ventured, nothing gained,
M
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Hopefully you will post what you find out from PT&G about airgun chamber reamers, I am sure they will cut anything you wish for a price. I would like to know since I am staring down the barrel of a chambering project myself and not looking forward to making and heat treating my own reamers. I am sure it is no big deal, but I am betting the first one is the toughest with lots of errors along the way. I may just cut them and pay a knife maker friend to do the heat treating for me since he has the proper oven and knowledge to do it.
Nothing ventured, nothing gained,
M
I called, the right guy was out of office until Monday. I will call back monday. I plan to ask about changing the 30 degree angle to X degree---I'm curious what the ideal angle would be.
In this hobby we all have capabilities and constraints. We are able to use our capabilities to identify workarounds for our constraints. Sometimes the only workaround is $$. Unfortunately for me, this is one of my constraints that will require $$ to solve. if Pacific Tool and Gauge can make a tool that allows me to rough drill a chamber, then precisely finish the chamber and lead or simply modify an existing lead with repeatable precision, without machine tools/skills, they can have my $$. If they can't, then I learned a bit more about the topic but didn't lose any $$ in the process.
I'll keep the thread alive as I learn more.
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I have made chamber reamers with a 1 deg. angle per side (from the C/L) and also a 2 deg.... The shallower angle allows a much longer tolerance in overall slug length and shape to be chambered without excessive force, and still engage the tapered leade to some degree.... It also reduces the force required to chamber a slug, because the very shallow taper on the land is more easily pressed into the nose (or front driving band) of the slug, engraving it to whatever depth is required to chamber so that the base is forward of the barrel port.... Here is an example of several slugs that have been chambered in my .257 cal, all to the same depth to the base.... This chamber was cut using a reamer of 1 deg. per side for the leade….
(https://i378.photobucket.com/albums/oo221/rsterne/6mm%20Sporter/257%20Bullets_zpshef0w8ul.jpg) (http://s378.photobucket.com/user/rsterne/media/6mm%20Sporter/257%20Bullets_zpshef0w8ul.jpg.html)
All seven slugs engage the leade to some degree.... The shortest slug on the right barely touches it, while the longest slug on the left is engraved to the full depth of the lands at the back edge of the nose.... and in fact the marks would have been quite a bit further back on that slug, if it were not for the recessed midbody, which is designed to prevent that, and reduce the bore drag.... The slug to the right of it is the same....
The back of the leade, where the parallel chamber starts, is just behind the front of the drive band on the right hand slug.... In fact, if you look closely at the bullet to its left, you can see the mark from the leade extending to the front of the forward lube groove.... and marks from the back of the leade in a similar location on the middle three slugs....
Incidently, there is a classic example of a poorly cut sprue, damaging the base of the slug, on the one third from the left.... You can see that the gas check stub is clearly bent to the left in the photo.... the base is rounded on the right, and bent out and pointed on the left, from the force of cutting the sprue.... Either the lead had not cooled sufficiently, and/or the hole in the sprue plate is too large....
Bob
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Bob, thank you for the post. I can see where reducing the angle allows for a much more broad range of length/weight slug.
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Here is a generic drawing of the way I make my reamers.... this example is for a .22 cal airgun barrel....
(https://i378.photobucket.com/albums/oo221/rsterne/22%20cal%20Disco%20Double/Reamer%20Side%20View_zpsiiqcmig8.jpg) (http://s378.photobucket.com/user/rsterne/media/22%20cal%20Disco%20Double/Reamer%20Side%20View_zpsiiqcmig8.jpg.html)
The leade starts in the recess immediately behind the pilot, and continues at a 1 deg. taper until it meets the chamber diameter.... The cutting occurs in the area marked as "Leade".... Here is the cross section, with dimensions in calibers....
(https://i378.photobucket.com/albums/oo221/rsterne/22%20cal%20Disco%20Double/Reamer_zpsywtq5w0p.jpg) (http://s378.photobucket.com/user/rsterne/media/22%20cal%20Disco%20Double/Reamer_zpsywtq5w0p.jpg.html)
The dotted lines are if you wish a single flute reamer instead of 3 flutes.... It is plunging the mill slightly past the centerline (~5% of caliber) that forms the cutting angle.... A professional tool company will have their own ideas, this drawing is just FYI....
Bob
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Woah, Thank You Bob! That was exactly the 'type' of drawing I was looking for. A specific drawing for .257 would have been more helpful, but (LOL) it will be easy enough to extrapolate a proper drawing for my needs from your illustration. I had attempted to make a cutter about a year ago but the geometry was wrong and it didn't cut. knowing about twice as much as I did a year ago I can see now that I should have gone past the centerline a little bit. Would it also be possible to take a 7 degree cutter and make the flute cuts ON centerline and have a similar effect?
Cheers,
M
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Not sure what you mean by a "7 degree cutter".... I assume you are not talking about the taper of the leade, but the angle of the cutting edge of the flute, in cross section?.... Would it surprise you to know that if you plunge the mill 5% of the diameter of the cutter below the C/L, you end up with a cutting angle of 5.75 deg?
Think about it this way.... Look at my drawing, and notice that there is a rectangle between the horizontal C/L and the depth of the flute.... It is 0.05 cal high, and 0.50 cal wide.... ie the ratio of height to width is 1:10.... If you now draw a diagonal from the center of the circle to where the edge of the flute is, the sine of that angle is 0.100, right?.... That works out to an angle of 5.75 deg.... If you want to increase the flute angle to a full 7 deg. then you would plunge the mill slightly deeper.... The sine of 7 deg. is 0.122, so multiply that by the radius of 0.50 cal and you would get 0.06 cal (ie. 6% of the caliber).... The deeper you plunge the mill past the centerline, the more aggressive the cutting angle of the flute.... so the reamer cuts faster, but the surface finish is not as good....
I have settled on 5% of the caliber as a nice compromise.... If you hone the edge with a diamond hone (on the flat where the end of the mill cut, NEVER touch the outside of the circle)…. when turned slowly and advanced slowly into the bore, you get fine shavings of metal as it removes the lands.... I use 28 RPM on my lathe, and advance the reamer very slowly, maybe 0.010" every 10 seconds.... Once I have advanced it 0.100" (nearly 2 minutes), I remove it and clear the chips, relube it and repeat.... Here is a photo of the reamer just after removing it from the bore....
(https://i378.photobucket.com/albums/oo221/rsterne/6mm%20Sporter/6mm%20Reamer%20Cutting%20Well_zpsfy9jj49s.jpg) (http://s378.photobucket.com/user/rsterne/media/6mm%20Sporter/6mm%20Reamer%20Cutting%20Well_zpsfy9jj49s.jpg.html)
The big pile of shavings sitting in the flute is from a single insertion of 1 turn of the handwheel on the tailstock, which is 0.100".... You can see by the shiny mark on the side of the flute just below the shavings where the cutting action occurs.... on the last part of the 1 deg. taper, just before the parallel section of the chamber.... As you can see, you must NOT keep going with your cutting, or the flute could clog up.... I remove the reamer and blow off the chips and relubricate every 0.100" of chamber depth.... This also gives you the opportunity to blow out the bore and check the fit of the slugs as you make the chamber deeper, so you know when to stop.... You MUST know where you want the base of the slugs to be when you are finished, of course.... I actually use the end of the reamer to push the slug into the bore a bit past where it stops by hand.... You can get a "feel" for how tight they are in the leade, and where you need to stop the chamber, for the selection of slugs you want to use.... You just knock the slug out from the muzzle each time with a cleaning rod.... If you have to pound on it, you forced the slug into the leade too far.... ;)
Bob
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Bob, wow I had to read that one twice just to make sure I got it.
Sorry, my reference to using a 7deg cutter was incomplete. It is in the 'dovetail' cutter family but only puts a 7deg taper on your cut, and is a common relief angle for cutting tools. Then you hit us with "Would it surprise you to know that if you plunge the mill 5% of the diameter of the cutter below the C/L, you end up with a cutting angle of 5.75 deg?"
I completely understand the concept now that the 'trig' was spelled out so amazingly well. However I would like to request some clarity with your wording in the following description. You mentioned "......The deeper you plunge the mill past the centerline, the more aggressive the cutting angle of the flute." Just so we are clear, are you lowering the cutter in the 'Z' axis with the quill (or raising the knee of the mill) to make the cut deeper with the tip of the endmill as opposed to moving the 'y' axis to make the cut deeper with the side of the endmill? I guess it depends on the orientation of the part in the mill as to which cutting edge you intend to cut deeper with. Which 'endmill cutting surface' makes a better cut for building a reamer?
I think I speak for everyone reading this thread, thank you for educating us on this topic, we appreciate it greatly.
M
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If you look at the photo of my reamer in Reply #2, you will see that it is the END of the mill that is past the centerline, so that the cutting edge of the flute is straight, from end to end.... If you use the side of the mill, then due to the radius of the tool, both ends of the cutting edge will arc upwards.... which means you have to increase the LOA to get the same flute cutting length.... I don't think that is the best way to make the reamer.... Having the cutting edge of the reamer a straight line also makes it much easier to hone with a diamond stone, IMO....
Additionally, using the side of the mill can cause a difference in the depth of cut depending on if you are "climb cutting" or cutting the other direction.... and if the end mill itself (or the reamer) flexes at all, it can chatter.... Although the end of the mill tends to leave circular marks, those aren't really an issue, and can be honed out before hardening, if you wish....
Incidently, when I install the reamer in the tailstock chuck, I put one flute groove on the top, to hold a large puddle of cutting oil (I also squirt some down the bore).... I use "Cool Tap" cutting oil, and it seems to work well for this application.... It comes in a small (4 oz.? ) squirt/dropper bottle, and I have had that one bottle for over a decade.... ::)
Bob
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I have ordered throat reamers from pacific tool and they have all worked very well. I believe the taper is 1* just like Bob uses but I do t have the tooling to actually measure it accurately. I’m presently waiting on a .172 throat reamer. I should mention it again that all you need is the throat reamer , the others are for cutting chambers for powder burners.
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I have ordered throat reamers from pacific tool and they have all worked very well. I believe the taper is 1* just like Bob uses but I do t have the tooling to actually measure it accurately. I’m presently waiting on a .172 throat reamer. I should mention it again that all you need is the throat reamer , the others are for cutting chambers for powder burners.
Thanks for the info Denis. I started out the new year with a cold so between rest and staying caught up with work I haven't taken the time to call Pacific tool yet. I hope to get in touch with them this week. I guess I misunderstood the tools and how they would work for us. I was thinking the necker would finish ream/size the chamber (slightly diameter than bore) then the throater would ream the tapered lead?
As I get more information I'll update the thread...
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I most cases, in a PB, the neck of the cartridge is significantly larger than the caliber, because the bullet fits inside the neck of the brass.... The exception is the .22 rimfire, where the base of the bullet has a smaller that caliber "heel" that fits inside the case, and the case OD is virtually the same as the bore....
So yes, you want a throat reamer, not a neck reamer....
Bob
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A cheaper way to do it is buy a reamer of your caliber. Take it to a tool grinder. Have them grind a pin on the end and put a 1 degree taper on it. Then make a bushing that fits your bore.
I do this for calibers I know I'm not going to do more then once or twice. My tool grinder will make one out of carbide for $135 though.
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I have a tool grinding company that modifies reamers to print. I just got a straight flute reamer modified with a 10-degree included angle for a .25 pellet barrel. It cut brilliantly, and cost me a week wait, and $46. Going to get another for my next barrel, a slow twist .300 pellet barrel from TJ's. I expect that reamer blank to be slightly more. Going to try a helical twist flute blank this time. I had them leave me a .125 stub up front for fitting a PEEK. Going to try a grooved one next time and make the pilot bushing from steel, custom fit for the barrel in hand.
cheers,
Douglas
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I have a tool grinding company that modifies reamers to print. I just got a straight flute reamer modified with a 10-degree included angle for a .25 pellet barrel. It cut brilliantly, and cost me a week wait, and $46. Going to get another for my next barrel, a slow twist .300 pellet barrel from TJ's. I expect that reamer blank to be slightly more. Going to try a helical twist flute blank this time. I had them leave me a .125 stub up front for fitting a PEEK. Going to try a grooved one next time and make the pilot bushing from steel, custom fit for the barrel in hand.
cheers,
Douglas
That sounds great, your previous posts about using a local tool grinder persuaded me to slow down this pursuit a bit and see what other options are available. I recently ordered a #7 taper pin reamer, with hopes of modifying it to create a lead on a .357 barrel that should arrive from TJ's this Friday. I ordered 30" of barrel, if I fail at DIY I can just cut off my failure and farm out the work, with a goal of maintaining 28" minimum barrel length.
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I might get blasted for saying this, but in my experience with airgun barrels having a lead is crucial for accuracy when shooting bullets. However, the precision of the lead matters little. I've used sand paper and a couple of dowels with a good bit of patience to produce a number of great shooting barrels. Sand the throat out completely, and the dowel/sand paper will cut a taper whether you want it to or not.
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I ended up modifying a #7 taper pin reamer, loosely following the method Douglas described. This was for a .357 TJ's 1:26 barrel, not the barrels that were the subject of this thread. I will modify those barrels using the same method at a later date.
I say loosely followed Douglas' instructions because I didn't take any measurements. I simply ran it into the raw bore until it was deep enough that it opened the chamber end up to the point where the base of a .358 slug would just fit. Then marked the reamer and reduced the diameter beyond the mark, towards the big end. Once a couple of inches were reduced to .345 or so I was finished.
Then I ran it into the bore slowly, frequently retracting and clearing chips. When clearing chips I would test fit an NSA 105gr. Once it was engaging rifling when seated just beyond the transfer port I was finished. I basically cut the chamber and lead all in one series of operations with the same tool. Then I finished lapping the breech end of the barrel.
It worked pretty well, at least from the looks of the lead and how it feels when slugging the barrel. It will be some time before I can do any accuracy testing. I was comfortable enough doing it that I ordered #2, #4, #5, #6 to use for making .177-.30 tools.
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Tapered Pin Reamers are 1/4" per foot, which works out to 1.2 deg. included angle.... which should work out great....
Bob
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Would a #5 ream be the one for .25/.257? What I think I am seeing is the start would be under sized then the ream would end with a larger size so that I can modify it like Mac described.
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A #5 tapered pin reamer starts at 0.2407" and ends at 0.2994".... A #4 starts at 0.2071" and ends at 0.2600".... Either would work for a .25 cal or .257 cal.... but the #4 could also be used in a .22 cal or .224 cal.... Since you probably would want to grind away the flutes after it reaches chamber diameter you would need two anyways.... A #3 will also work for .22 cal or .224 cal, it starts at 0.1813" and ends at 0.2294".... A #2 would be the size for .177 cal, it starts at 0.1605" and ends at 0.2010".... A #6 would work for .30 cal or .308 cal, it starts at 0.2773" and ends at 0.354".... As mentioned above, the #7 is for .35 and .357 cal....
Bob
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A #5 tapered pin reamer starts at 0.2407" and ends at 0.2994".... A #4 starts at 0.2071" and ends at 0.2600".... Either would work for a .25 cal or .257 cal.... but the #4 could also be used in a .22 cal or .224 cal.... Since you probably would want to grind away the flutes after it reaches chamber diameter you would need two anyways.... A #3 will also work for .22 cal or .224 cal, it starts at 0.1813" and ends at 0.2294".... A #2 would be the size for .177 cal, it starts at 0.1605" and ends at 0.2010".... A #6 would work for .30 cal or .308 cal, it starts at 0.2773" and ends at 0.354".... As mentioned above, the #7 is for .35 and .357 cal....
Bob
Bob, thanks for this information, I just order a #4.
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Let us know what mods you did to it, and how it works....
Bob
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Be careful when you order. There are #4 reamers, and there are 4/0 reamers. Very different. I don't know why.
Maybe this:
https://www.amazon.com/Drillco-High-Speed-Reamer-Spiral-Uncoated/dp/B00GR5Y3C8/ref=sr_1_23?keywords=%234+HIGH+SPEED+STEEL+SPIRAL+FLUTE+TAPER+PIN+REAMER&qid=1581181890&sr=8-23#feature-bullets-btf (https://www.amazon.com/Drillco-High-Speed-Reamer-Spiral-Uncoated/dp/B00GR5Y3C8/ref=sr_1_23?keywords=%234+HIGH+SPEED+STEEL+SPIRAL+FLUTE+TAPER+PIN+REAMER&qid=1581181890&sr=8-23#feature-bullets-btf)
I don't see the whole specifications so please verify the size.
Hunter
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I believe a # 4/0 reamer is a # 0000 (called a "four ought" ).... ie a lot smaller than a # 0.... You want a # 4....
Bob
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Be careful when you order. There are #4 reamers, and there are 4/0 reamers. Very different. I don't know why.
Maybe this:
https://www.amazon.com/Drillco-High-Speed-Reamer-Spiral-Uncoated/dp/B00GR5Y3C8/ref=sr_1_23?keywords=%234+HIGH+SPEED+STEEL+SPIRAL+FLUTE+TAPER+PIN+REAMER&qid=1581181890&sr=8-23#feature-bullets-btf (https://www.amazon.com/Drillco-High-Speed-Reamer-Spiral-Uncoated/dp/B00GR5Y3C8/ref=sr_1_23?keywords=%234+HIGH+SPEED+STEEL+SPIRAL+FLUTE+TAPER+PIN+REAMER&qid=1581181890&sr=8-23#feature-bullets-btf)
I don't see the whole specifications so please verify the size.
Hunter
Hunter,Good point, I did notice the same thing and I ordered the #4 and not the #4/0.
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Let us know what mods you did to it, and how it works....
Bob
The first one that I plan to do with it is the .22 Liberty which has a large step, as seem with a bore scope, that is excessive with an undersized bore (.214"). If it works out I will check out my other toys and order the appropriate reamer. It always bother me but I did not want to spend $50 for the proper reamer and I almost got in there with Dremel mounted in a lathe. I think that the reamer will work out OK. Good find...thanks.
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I don't know which one you ordered, but I chose the spiral fluted one. The one that I have is no longer available.
The spiral is to the left, but the cutting edge is to the right. This prevents it from pulling itself into the work. It cuts clockwise just like a regular drill. When you reverse the tool it clears the chips.
I chose the spiral flutes because I thought that a straight flute would chatter on the rifling.
Please note that I am NOT a machinist.
Hunter
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I don't know which one you ordered, but I chose the spiral fluted one. The one that I have is no longer available.
The spiral is to the left, but the cutting edge is to the right. This prevents it from pulling itself into the work. It cuts clockwise just like a regular drill. When you reverse the tool it clears the chips.
I chose the spiral flutes because I thought that a straight flute would chatter on the rifling.
Please note that I am NOT a machinist.
Hunter
Hunter, I also ordered the spiral reamer. I was told many years ago that you should never turn a reamer in the reverse direction as it will dull it.
I don't know now true it is but I followed his directions.
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Yes, if all else fails, follow the directions.
I never reversed it, it was in the description of the one that I bought.
The amount of chips is very small. Most of the chips stay in the reamer and cutting oil.
It does push the chips into the breech. Clean it well.
Hunter