# Tips For Dialing In And Indicating Tube With Steady Rest?



## shooter123456 (Sep 7, 2016)

I need to thread a 1.5" 316 seamless tube on my PM 1030v lathe.  I have done this kind of thing in the past with a HF 7x12 lathe but it was kind of a hack job and I wan't more precision now. 

I turned down a plug to put in the tube until it was a very tight fit.  Then I stuck it in the 4 jaw and tried to indicate it as true as I could at the spindle. I was able to get it to about .004" and then I was getting two peaks and two lows.  As in jaw 1 was 0.00", jaw 2 was .004", jaw 3 was .000" and jaw 4 was .004 again.  That made me think it was ovalled out.  Am I expecting too much from the tube?  Should I turn down a slightly larger plug and use a mallet to force it in? Is there a way to tell if the tube is no good?  The first tube was no good, I think from my cut off saw.  It was bent all over the place.

Once I get it dialed in at the spindle, whats the best way to get it dialed in straight? When I got it dialed to .004" it was off by about .030" at 12" out.  Is there a way to dial it in at the steady while keeping it straight?


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## WesPete66 (Sep 7, 2016)

I hardly have any answers, but maybe have some thoughts to consider..
As to the condition of the tube, if you were to put it on a v-block and turn it under a dial indicator you would get an idea of how round the part itself is. If it then ovals out in the chuck, then you know where the trouble lies.
I had the same question about the steady rest. What I found is that you mount the test indicator onto the face of the chuck with the point resting on the far end of the part near the steady. Then as you turn the chuck/part the indicator reading tells you which way to adjust the steady rest rollers.  (I have yet to gather the test indicator and holder to allow me to try this..) I did find some good youtube vids showing this.


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## Tony Wells (Sep 7, 2016)

If it's not too rigid (read: too tight in the chuck) just knock it around with your palm out where the rest is going to run. Or another way is to pick a spot somewhere close to the chuck where it can be made run true, and slide the steady rest to that point and adjust the rest there, then move it out where you want to run it. Generally there isn't enough wear on the bed to cause alignment issues for this. Yet another way is to make or get a live center for the tailstock and after indicating at the chuck, adjust the steady rest with the tailstock in the tube.

Edit to add: You can't use the tailstock to help if you have only a sawed tube. It should be machined flat and square. That said, of course you need the steady to face it square. It's a catch 22. You can probably get it close enough just bumping it around to face it, then go to the center/tailstock to get the steady right on. The problem is that if the steady is not adjusted to run on the spindle centerline, the work WILL walk out while rotating. But a quick facing cut won't take long, and the walking out won't happen all at once. Just don't start the lathe and walk off. Start it, get it cut, and stop it.

I would add though, that 0.008 out of round is not going to run well in your steady rest. And vee blocks can be misleading, because they are providing 2 points of contact @45° while your indicator is running on one. Some of the egg won't show, depending on how many lobes there actually are. Same with a mic. It only shows the difference between 2 point measurements. Some out of round conditions won't show with that method either. Roundness can be a little tricky.


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## Tozguy (Sep 7, 2016)

What Tony said.
What is the wall thickness of the pipe?
With a steady I'd be concerned about the pipe walking out of the 4 jaw. What about putting a plug in both ends and holding the pipe between centers?


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## shooter123456 (Sep 7, 2016)

WesPete66 said:


> I hardly have any answers, but maybe have some thoughts to consider..
> As to the condition of the tube, if you were to put it on a v-block and turn it under a dial indicator you would get an idea of how round the part itself is. If it then ovals out in the chuck, then you know where the trouble lies.
> I had the same question about the steady rest. What I found is that you mount the test indicator onto the face of the chuck with the point resting on the far end of the part near the steady. Then as you turn the chuck/part the indicator reading tells you which way to adjust the steady rest rollers.  (I have yet to gather the test indicator and holder to allow me to try this..) I did find some good youtube vids showing this.


I will give it a try with V-blocks.  I think it was only ovalled near the chuck and the fact that it was consistent makes me think it was bent by the chuck. Ill try a new plug then use a dial at the chuck and near the end and see what I can do.


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## shooter123456 (Sep 7, 2016)

Tony Wells said:


> If it's not too rigid (read: too tight in the chuck) just knock it around with your palm out where the rest is going to run. Or another way is to pick a spot somewhere close to the chuck where it can be made run true, and slide the steady rest to that point and adjust the rest there, then move it out where you want to run it. Generally there isn't enough wear on the bed to cause alignment issues for this. Yet another way is to make or get a live center for the tailstock and after indicating at the chuck, adjust the steady rest with the tailstock in the tube.
> 
> Edit to add: You can't use the tailstock to help if you have only a sawed tube. It should be machined flat and square. That said, of course you need the steady to face it square. It's a catch 22. You can probably get it close enough just bumping it around to face it, then go to the center/tailstock to get the steady right on. The problem is that if the steady is not adjusted to run on the spindle centerline, the work WILL walk out while rotating. But a quick facing cut won't take long, and the walking out won't happen all at once. Just don't start the lathe and walk off. Start it, get it cut, and stop it.
> 
> I would add though, that 0.008 out of round is not going to run well in your steady rest. And vee blocks can be misleading, because they are providing 2 points of contact @45° while your indicator is running on one. Some of the egg won't show, depending on how many lobes there actually are. Same with a mic. It only shows the difference between 2 point measurements. Some out of round conditions won't show with that method either. Roundness can be a little tricky.


There is a way to determine whether it is "Too rigid"?  When I use the 4 jaw (only had a 4 jaw about a month now though) it tends to be incredibly tight with the loosen the lows and tighten the highs technique. 

I could probably run a dial test indicator and a dial indicator (I have 1 of each but 2 of niether) near the chuck and near the end and see if I can get both of them steady.  Maybe get the 4 jaw close, then loosen it and tap it with my hand?  Would a 3 jaw be better in this case?  My 3 jaw tends to do pretty well.

The more I think about it, I think my plug must have been undersized.  If it was .002" undersized, which would make sense if there was a burr in the tube from when the supplier cut it off (I can't remember if I checked for one which makes me think I didn't), when I squeezed in, part would shrink to -.002" then the other two sides would swell to +.002" which would account for the .004 .000 .004 .000 reading. I didn't leave it in the chuck and I hope it won't stay that way.  It was only chucked for 15 minutes tops.


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## shooter123456 (Sep 7, 2016)

Tozguy said:


> What Tony said.
> What is the wall thickness of the pipe?
> With a steady I'd be concerned about the pipe walking out of the 4 jaw. What about putting a plug in both ends and holding the pipe between centers?


Its 1.5" OD 316 seamless with .065" walls for 1.37" ID.  I have to thread the inside so I could only plug one end.  I suppose I could do both to get it running true then set the steady rest.  It would be tough to remove the plug though wouldn't it?


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## Wreck™Wreck (Sep 7, 2016)

Tubing is not round, the larger the less round it is. If you want to prepare it for a steady put  something on the tailstock end, it doesn't have to be a plug nor fit in the ID, indicate it there and knock it around with a mallet until it is as close as possible then do the chuck end. Tighten and lock the TS quill and if permitted  turn a band on the OD away from the threads wide enough for the steady rollers, on such a small DOM tube this may require only a few .001's, set the steady there and go to town.

If a band is not permitted use a Catshead. You will notice that nearly every hydraulic cylinder has a steady rest band near the open end. Running a part that is even slightly out of round in a steady will result in the same or more error on the turned diameter.

As a side note if you use a steady with roller bearings DO NOT let chips get between the rollers and work or Catshead. I broke the frame of a steady on a 20"+ lathe this way, the steady had to get bigger or the work smaller, the work won and the casting broke.

I do it this way


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## shooter123456 (Sep 7, 2016)

Wreck™Wreck said:


> Tubing is not round, the larger the less round it is. If you want to prepare it for a steady put  something on the tailstock end, it doesn't have to be a plug nor fit in the ID, indicate it there and knock it around with a mallet until it is as close as possible then do the chuck end. Tighten and lock the TS quill and if permitted  turn a band on the OD away from the threads wide enough for the steady rollers, on such a small DOM tube this may require only a few .001's, set the steady there and go to town.
> 
> If a band is not permitted use a Catshead. You will notice that nearly every hydraulic cylinder has a steady rest band near the open end. Running a part that is even slightly out of round in a steady will result in the same or more error on the turned diameter.
> 
> ...



I appreciate your response.  There are a few parts I do not understand.  First when you say "put something on the tailstock end and indicate it there".  What are you suggesting I put on the tailstock end?  Are you just saying to put it in the chuck, get the tail end turning true with a mallet, then get it turning concentric using the chuck? Also you say "Tighten and lock the TS quill" what would I be tightening it against?

Unfortunately, I can't turn a band on the tube for the steady rest.  I can't make the tube any thinner than it already is.  Regarding a catshead, would I have the chuck hold that or is the best bet to attach it to the tube then turn the catshead in the steady rest? I don't have one now so I would have to make it.  Can you suggest a material for it?

I use a steady with bronze tips.  I try to keep it pretty clean but is it as much of a concern as with the roller bearings?

Again I really appreciate you sharing the knowledge.  I came here to learn and feel like I am getting exactly what I need.


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## JimDawson (Sep 7, 2016)

Tozguy said:


> What about putting a plug in both ends and holding the pipe between centers?



I think @Tozguy has the right idea here.  Trying the thread a tube that is slightly out of round in a steady rest is not going to go well.

As it is the threads are not going to be a consistent depth or form.  Holding this in a steady rest will make the problem worse.


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## shooter123456 (Sep 7, 2016)

JimDawson said:


> I think @Tozguy has the right idea here.  Trying the thread a tube that is slightly out of round in a steady rest is not going to go well.
> 
> As it is the threads are not going to be a consistent depth or form.  Holding this in a steady rest will make the problem worse.


I think the ovalling was created by the plug being about .002" undersized.  My guess at the moment is that there was a burr on the tube from when the supplier cut it and I didn't remove it before testing for a slip fit.  Then when I tightened the jaws, 2 sides bowed in .002" and two bowed out .002" creating the .004 .000 .004 .000 readings I was getting.  I am going to clean out the burr (if there is on one of course) and turn a new plug and see if that makes a difference. I don't think I mentioned but I was able to force it to about .001" using the steady but it seemed to be a very strained fit and I was to tired/frustrated to continue so I called it a day.


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## brino (Sep 7, 2016)

Hi shooter,

I'd also start at the beginning. Depending on the tube wall thickness, material, how it was manufactured, and how it is cut you may be starting off on the wrong foot.

is the tubing manufactured by folding and welding? if so it may have a seam on the inside diameter that interferes with the plug you made
are you crushing the tube in a vise when cutting it, making it out of round before even getting to the lathe?

are you making it out of round with the cut alone? thin walled tube can easily be forced out of round with the force of a bandsaw or other blade. Also, they can throw up burrs on the edges that need to be dressed.
Try to eliminate any of those problems first.

Is there any way that you can mount your 3-jaw chuck in the tail-stock to help you align that end while you get the stead-rest roughly aligned? If so, you could:

use the 4-jaw chuck in the head-stock grab one end of the stock holding but loosely,

use the 3-jaw chuck in the tail-stock grab the other end of the stock again loosely,
place the fixed steady where it needs to be again loosely,
remove the 3-jaw tail-stock support
dial in the tube at the steady rest as best you can, tighten without distorting the tube

dial in the tube at the 4-jaw/head-stock, tighten without distorting the tube
double check the centering at both ends
All the above is done without the lathe running, turn by hand to see the indicators move.
Temporary plugs may be required if the tube is so thin that the chucks or steady alone change it's shape.

Good Luck, and please let us know how it goes! (what worked, and what didn't)

-brino


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## brino (Sep 7, 2016)

shooter123456 said:


> I was to tired/frustrated to continue so I called it a day.



That is always the right choice!
-brino


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## shooter123456 (Sep 7, 2016)

brino said:


> Hi shooter,
> 
> I'd also start at the beginning. Depending on the tube wall thickness, material, how it was manufactured, and how it is cut you may be starting off on the wrong foot.
> 
> ...


The tube is 316 stainless DOM (supposed to be seamless they tell me) 1.5" OD with .065" walls. Its for a rifle suppressor so concentricity is pretty important. 

I havent cut it myself at all. It was ordered from online metals at 12". I cant say how they cut it. I would assume band saw but I really dont know. I planned to use a razor sharp cut off tool to avoid bending it when I cut it from 12" to 7.8. 

I really dont have a way to mount the 3 jaw in the tail stock. Its a 5" chuck and the tailstock is MT2 taper. 

Is setting the steady rest before setting the chuck standard? If I went with the 3 jaw instead of the 4, would the pressure be more evenly distributed and cause less distortion?


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## Tozguy (Sep 8, 2016)

shooter123456 said:


> Its 1.5" OD 316 seamless with .065" walls for 1.37" ID.  I have to thread the inside so I could only plug one end.  I suppose I could do both to get it running true then set the steady rest.  It would be tough to remove the plug though wouldn't it?



Cutting good threads inside that pipe under these conditions is a considerable challenge. Knowing what the part is intended for, and taking inspiration from motorcycle mufflers, could a sleeve be made that is threaded inside and then permanently fixed in the end of the pipe?


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## Tozguy (Sep 8, 2016)

shooter123456 said:


> The tube is 316 stainless DOM (supposed to be seamless they tell me) 1.5" OD with .065" walls. Its for a rifle suppressor so concentricity is pretty important.
> 
> Is setting the steady rest before setting the chuck standard? If I went with the 3 jaw instead of the 4, would the pressure be more evenly distributed and cause less distortion?



No, it would be worse. A six jaw chuck would be better than the 4 jaw for thin pipe. But that is $$$$.


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## Charles Spencer (Sep 8, 2016)

I'd make it from bar stock.  Skim cut, bore and thread it, and turn it to size on a mandrel.


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## John Hasler (Sep 8, 2016)

Charles Spencer said:


> I'd make it from bar stock.


Or at least from thick wall tubing.


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## shooter123456 (Sep 8, 2016)

John Hasler said:


> Or at least from thick wall tubing.


How thick would it need to be to not be any trouble?


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## shooter123456 (Sep 8, 2016)

Tozguy said:


> No, it would be worse. A six jaw chuck would be better than the 4 jaw for thin pipe. But that is $$$$.


I would like to get a 6 jaw, but as you said, $$$$.  There is never enough going around to do everything I want to do...


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## shooter123456 (Sep 8, 2016)

Tozguy said:


> Cutting good threads inside that pipe under these conditions is a considerable challenge. Knowing what the part is intended for, and taking inspiration from motorcycle mufflers, could a sleeve be made that is threaded inside and then permanently fixed in the end of the pipe?


Im not sure.  The way I designed the suppressor, the baffles are a tight fit with the ID of the tube so any insert would have to be the same size as the ID of the tube.


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## talvare (Sep 8, 2016)

Do you have a 5C collet system for your lathe ? If so, I would use a step collet to support the part at the head stock. I have used them for thin walled pieces and they work very well and cause no distortion of the part. You purchase them in "blank form" and machine a pocket that exactly fits the OD of your part to be turned. Then dial in the other end in your steady rest. The link below shows an example of a step collet.

Ted

http://www.ajaxtoolsupply.com/5cstc...5cstclco3hed&gclid=CNbN89j__84CFQqPfgodLqQHrg

Just thought of another option. Machine a set of pie jaws for your 3-jaw chuck to fit the tubing. These also will chuck the part without distortion.


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## shooter123456 (Sep 8, 2016)

talvare said:


> Do you have a 5C collet system for your lathe ? If so, I would use a step collet to support the part at the head stock. I have used them for thin walled pieces and they work very well and cause no distortion of the part. You purchase them in "blank form" and machine a pocket that exactly fits the OD of your part to be turned. Then dial in the other end in your steady rest. The link below shows an example of a step collet.
> 
> Ted
> 
> ...


I don't have any kind of collet system for it yet.  I was looking into an MT4 -> 5C adapter for it but I haven't found one yet.  Those step collets look like a promising option though.  I didn't know they made collet blanks either. That may come in very handie for a few future projects.


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## talvare (Sep 8, 2016)

shooter123456 said:


> I don't have any kind of collet system for it yet.  I was looking into an MT4 -> 5C adapter for it but I haven't found one yet.  Those step collets look like a promising option though.  I didn't know they made collet blanks either. That may come in very handie for a few future projects.



The nice thing with those step collets is that if you don't machine the pocket too deep, you can machine multiple steps into them and make one collet useful for several different diameter parts.

Ted


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## John Hasler (Sep 8, 2016)

shooter123456 said:


> How thick would it need to be to not be any trouble?


I guess I'd want at least .109" but I don't see anything suitable in the Online Metals listing (besides, you've already got what you've got).  Perhaps you could make a sleeve to fit over the OD to support the tube while threading (your steady rest would run on the OD of the sleeve).  Then use a mandrel while turning the OD of the tube.


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## shooter123456 (Sep 8, 2016)

John Hasler said:


> I guess I'd want at least .109" but I don't see anything suitable in the Online Metals listing (besides, you've already got what you've got).  Perhaps you could make a sleeve to fit over the OD to support the tube while threading (your steady rest would run on the OD of the sleeve).  Then use a mandrel while turning the OD of the tube.


Sounds like it would be worth a shot.  Should I go with a very tight fit or should it be a slip fit and adhesive?


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## Tozguy (Sep 8, 2016)

shooter123456 said:


> Sounds like it would be worth a shot.  Should I go with a very tight fit or should it be a slip fit and adhesive?



very tight fit. 
adhesive might stain the stainless. 
once the inside of the pipe is threaded would the sleeve have to be removed?


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## shooter123456 (Sep 8, 2016)

Tozguy said:


> Very tight fit. If you heat the sleeve and freeze the pipe you will get an extra tight fit.
> Adhesives are good but depend on how hot the part will get in use?


I assumed it would be removed after the thread was cut. Though in use it will probably get to 400F regularly, occasionally as high as 900F would be possible.


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## John Hasler (Sep 8, 2016)

You're going to turn down the OD anyway: just machine the sleeve off.


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## shooter123456 (Sep 8, 2016)

John Hasler said:


> You're going to turn down the OD anyway: just machine the sleeve off.


At this time there is no plan to turn down the OD of the tube. I dont want to dance the edge with pressure and risk it failing.


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## brino (Sep 8, 2016)

John Hasler said:


> Perhaps you could make a sleeve to fit over the OD to support the tube while threading (your steady rest would run on the OD of the sleeve).



@John Hasler that is some great inside-out thinking! 
I will have to remember that.
-brino


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## Wreck™Wreck (Sep 8, 2016)

I will give you a step by step description of the process, I do not have the inclination to make a video and if I tried would probably get fired for showing Customer parts. With an illustration however.

Steps
1 Place steady on ways well towards the chuck

2 Place part in chuck through steady, if worried about marring the part with the hard jaws buy some cheap aluminum flashing that may be cut with scissors from Home Depot and wrap a few layers around it, you are using a 4 jaw.

3 Indicate the part at the chuck

4 Place a flat something with a hole against the end and apply the center with little pressure at this time, it does not matter if the end is saw cut and not square as this is not what you are measuring. Indicate this end and knock it into the least run out that you can get with a bit of wood or plastic, and a hammer if it is a large heavy part, you may want to indicate at the chuck again but I mostly find this unneeded  if the work at the TS end is short

5 Once minimum run out is gained tighten the TS quill on the part and lock it

6 Either cut a band for the steady (even without a plug the tail stock will hold the part for the light cut that a band requires), if this is prohibited install a cats head and indicate as close a possible using the 4 set screws that you cleverly installed just like a 4 jaw chuck, place some of that cheap flashing under the set screws so as not to mar the finish

7 Move steady into position and set the fingers or rollers gently, I have only used steadies with bearing rollers for the last 25 years I rotate the spindle until the rollers begin to rotate.

8 remove TS

9 Face, turn and thread

The chips will not roll under the solid fingers, when running a steady on a finished surface it will leave a mark rollers or fingers, keep that in mind.

This will consume a bit of time but you are a hobbyist and have plenty of that.

I do it for a living and have time quote constraints, could do the above mentioned work in 20-30 minuites on 1 1/2" DOM tubing, however I do not have to obsess over the dimensions, with a few exceptions most of the +2" tube parts that I make have -.005 +.000 if an inside part and +.000 - .002 if a bearing bore.

Good luck


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## gi_984 (Sep 8, 2016)

shooter 123456,
     Assuming you have your Approved Form 1 for this build, I'd recommend using round stock over tubing.  You'll be miles ahead in time and frustration.

I've got a lot of experience with factory cans and DIY.  If I was to build one today it would be similar to these

http://www.griffinarmament.com


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## gi_984 (Sep 8, 2016)

Checkout www.speedymetals.com
Decent selection of meals at reasonable cost.  They have thick walled pipe you could turn.  That would give you more wiggle room so to speak.


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## John Hasler (Sep 8, 2016)

shooter123456 said:


> At this time there is no plan to turn down the OD of the tube. I dont want to dance the edge with pressure and risk it failing.


Ok.  How about an aluminum sleeve?  You can use heat to put it on with a light shrink-fit and then use heat to get it off again.  It can also aid your facing operation.


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## Tony Wells (Sep 8, 2016)

I may have some heavier walled 13-8 about that size if you don't mind some tough to cut material. I could cut and true up a length of it if you wanted it. It larger on the OD, so you would end up turning it, but it would allow you some room to play with runout, etc.

You mentioned pressures. What range do you expect this to see and did you do the engineering to determine that 316 will do it? It's not particularly high strength, as ss alloys go.


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## shooter123456 (Sep 9, 2016)

gi_984 said:


> shooter 123456,
> Assuming you have your Approved Form 1 for this build, I'd recommend using round stock over tubing.  You'll be miles ahead in time and frustration.
> 
> I've got a lot of experience with factory cans and DIY.  If I was to build one today it would be similar to these
> ...


I have the form 1 in hand for this one.  I have the endcaps, baffles, and spacers finished already.  Just have the tube and blast baffle left. 




It mounts directly to the muzzle brake and should suppress 300 BLK very well and 308 relatively well.  The cone baffles are supposed to perform best with lower pressures. 

I considered going with round stock for it but it added considerable cost and when I did this with my first suppressor on the 7x12 harbor freight lathe, it wasn't too tough.  

What do you mean it would be similar to the griffin cans?  They have a very diverse product line...


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## shooter123456 (Sep 9, 2016)

John Hasler said:


> Ok.  How about an aluminum sleeve?  You can use heat to put it on with a light shrink-fit and then use heat to get it off again.  It can also aid your facing operation.


It sounds like this is probably the best way to go.  I will try a catstail first because I have a few other projects it would work well for too.


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## shooter123456 (Sep 9, 2016)

Tony Wells said:


> I may have some heavier walled 13-8 about that size if you don't mind some tough to cut material. I could cut and true up a length of it if you wanted it. It larger on the OD, so you would end up turning it, but it would allow you some room to play with runout, etc.
> 
> You mentioned pressures. What range do you expect this to see and did you do the engineering to determine that 316 will do it? It's not particularly high strength, as ss alloys go.


I appreciate the offer but wow that stuff is expensive.  I think I would struggle to turn it well though and wouldn't want it to go to waste.

The can will be going on a .308 rifle, 300 blk SBR, and a 16" .223 rifle.  I don't remember what pressures it would be put up against off the top of my head but I did the math, ran it past the people at silencertalk and we were good to go.  With the .065" wall, there was a decent safety margin as well.


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## gi_984 (Sep 9, 2016)

shooter 123456,
     Very good.  I'm active duty military with a background that provided me with a lot of experience with factory cans and then I started machining after taking classes at my local tech school.  I've had students as well as hobbyists ask me about making suppressors.  So not a big deal as long as we educate people to keep everyone out of trouble.
     I've used AAC, Gemtech, KAC, SWR, and AWC cans on various rifles (select-fire & precision), sub-guns, and a few pistols.  Things I liked and disliked about every model.  For home builds I like good knurling and spanner pin holes on the end caps.  I like the way Griffin adds cut outs on the end of the tube itself to provide a grasping point.  Having multiple endcaps for different center-fire calibers is the way to go if you are making a multi-caliber can.  But not for .22.lr.  I recommend a dedicated .22 l.r. only can.  Much lighter weight wise for construction.
     New users are shocked at how much fouling/blowback they get in their AR style rifles the first time they use a can.  Each can is different.  So don't burn thru a bunch of magazines to find you have an unacceptable level of fouling & buildup.  I've seen some baffles almost welded together from the fouling.  On that note it is worth the time to polish your baffles and the inside of the tube as much as possible.  I also use Bostik brand anti-seize grease on the threads of the endcaps.
Shooting a select-fire gas operated gun will increase the cyclic rate (i.e. boost effect).  Number your inner baffles!  Helps with re-assembly and rotating them so they wear more evenly.    
     Is the .308 a semi/auto or a bolt gun?  If you make a dedicated can for a bolt gun you can get away with a easier to machine material for the blast baffle.  For all around use I would use 17-4.


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## shooter123456 (Sep 9, 2016)

gi_984 said:


> shooter 123456,
> Very good.  I'm active duty military with a background that provided me with a lot of experience with factory cans and then I started machining after taking classes at my local tech school.  I've had students as well as hobbyists ask me about making suppressors.  So not a big deal as long as we educate people to keep everyone out of trouble.
> I've used AAC, Gemtech, KAC, SWR, and AWC cans on various rifles (select-fire & precision), sub-guns, and a few pistols.  Things I liked and disliked about every model.  For home builds I like good knurling and spanner pin holes on the end caps.  I like the way Griffin adds cut outs on the end of the tube itself to provide a grasping point.  Having multiple endcaps for different center-fire calibers is the way to go if you are making a multi-caliber can.  But not for .22.lr.  I recommend a dedicated .22 l.r. only can.  Much lighter weight wise for construction.
> New users are shocked at how much fouling/blowback they get in their AR style rifles the first time they use a can.  Each can is different.  So don't burn thru a bunch of magazines to find you have an unacceptable level of fouling & buildup.  I've seen some baffles almost welded together from the fouling.  On that note it is worth the time to polish your baffles and the inside of the tube as much as possible.  I also use Bostik brand anti-seize grease on the threads of the endcaps.
> ...



Wow... I really wish I came here to ask questions before I started.  I would have come out with a much much better can.  I really appreciate the wealth of knowledge you guys all have to share. 

Here is the original design that came to after a couple rounds of revisions with the guys at silencertalk:



The idea was that the muzzle brake would be a sacrificial blast baffle since I can make and replace those as often as I want.  From what I understand, the erosion of the blast baffle is primarily around the bore hole as thats where the unburnt pressurized powder is sent and essentially sandblasts it.  I am far from an expert though so I have deferred to the judgement of those that are more experienced.  The plan was to go with 17-4 for the blast baffle, but I haven't been able to find any in small amounts and I haven't been able to justify the cost.  At this point, plan A is to use the 303 I have on hand and if I have erosion problems in a few years, there is an 07/02 about half an hour from me that can turn me a new one out of 17-4 and destroy the old one. 



gi_984 said:


> Having multiple endcaps for different center-fire calibers is the way to go if you are making a multi-caliber can.



I was told this was a no go.  Since the ATF considers every part of a silencer a silencer in itself, any extra parts would consitute having an extra silencer.  I was told manufacturers had to get specific permission for each design and home builders were not allowed that exemption.  If that isn't true, I would love to turn an extra end cap for .556 to improve their performance on the ARs.



gi_984 said:


> New users are shocked at how much fouling/blowback they get in their AR style rifles the first time they use a can.  Each can is different.  So don't burn thru a bunch of magazines to find you have an unacceptable level of fouling & buildup.  I've seen some baffles almost welded together from the fouling.  On that note it is worth the time to polish your baffles and the inside of the tube as much as possible.  I also use Bostik brand anti-seize grease on the threads of the endcaps.



I was told to expect that with my first one and it is very true.  100 rounds suppressed through an SBR is dirtier than 1000 rounds through an unsuppressed 16" rifle.  I couldn't believe just how much dirtier they ran but they are a mess. The gas in the face is a pain in the butt too.  I have been sitting on ways to completely seal the upper so gas only vents through the ejection port and out the side of a gas buster. I keep putting that off because there are other things I want to do first... Regarding the fouling and build up inside the can, a thread on silencertalk said that was unavoidable and people just dip their suppressors when they seize up and its no big deal.  I figured that was just part of using suppressors. 



gi_984 said:


> Shooting a select-fire gas operated gun will increase the cyclic rate (i.e. boost effect). Number your inner baffles! Helps with re-assembly and rotating them so they wear more evenly.
> Is the .308 a semi/auto or a bolt gun?



I wish select fire was something I had to consider with this suppressor... Maybe one day if that registry is opened back up or I do very well when I finish school.  Heres to hoping. 

I hadn't thought to number the baffles. My plan was to measure them once machining was finished and stack them by thickness so the strongest are in the rear and the thinnest are in the front.  I was going for .065" with them and then with several lightened them up to the .050" range.  Is there a way to could recommend to number them that will stand up to cleaning and the beating everything inside will take? 

The .308 is a bolt gun.  24" Savage 10 FCP-SR.  Its a hoot and a half to shoot. I anticipate the new suppressor will be used mostly on the .308 and a 300 blk SBR using 230 gr cast and coated subsonic ammo. Neither of those are supposed to be particularly tough on cans.  If it goes a .556, it will probably be used on my match gun which I have shooting 55 gr FMJ at about 2500 FPS so there is very little pressure in that one as well.


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## Tony Wells (Sep 9, 2016)

300 vs 17-4? No contest. I wouldn't waste time on any 300 series if there was 17-4 available. Age to H-900 after complete machining and you should be good to go and it likely outlast everything else in the can. While the chemical resistance may not be as great, mechanically there is no comparison. In H-1025 machines better than annealed. Even that is better than 300 series, but annealed then H-900 is the way to go, and is about the easiest heat treat there is.


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## gi_984 (Sep 9, 2016)

shooter 123456,
     Good to have a friendly SOT nearby.  Unless things have changed drastically, you should still be able to make extra end caps as long as you mark it the same as the tube and build it together as a set.  For marking?  I have several sizes of metal hand stamps (letter & number).  ENCO used to be a good place to buy them especially when they had a discount code.  Lots of arsenals hand stamped serial numbers.  FN and Imbel would hand stamp the serial numbers on the bolts and BCs of the FALs.    
     The ideal scenario is to have a dedicated can for each type & caliber of weapon.  Anything else means you have to make compromises to accommodate different weapons.   Easier said  when it is for work/official entity  versus an individual citizen.   
     Please PM and I can give you more specifics on loads/etc offline.  Let's keep the forum responses more targeted to the machining specifics.


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