|
|
Post by Flatland Hunter on May 8, 2008 0:37:06 GMT -5
KerryB, I believe you posted info a while back about homebrew vents?
I picked up the screws from Granger and the drill bits from the site you posted.
My question's... I have the Dremel chuck and a friends drill press... what else do I need to get and what advice do you have on the actual drilling of the vent. Cutting oil type, is it needed, etc.?
Thanks!
Robbie
|
|
|
|
Post by Harley on May 8, 2008 7:25:40 GMT -5
Not KerrryB, but:
1. At Home Depot, buy a tap and drill bit set: Irwin-Hanson #80221. This is a 10-32NF plug tap and #21 drill bit.
2. Obtain a small scrap piece of bar steel with a thickness at least exceeding the length of the vent liner.
3. Drill and tap the steel, using a drill press to ensure that the steel plate is level.
4. You'll probably find no more than one choice of cutting oil, so buy whatever you find.
5. My drill press will close on the tiny vent liner drill bits; if yours doesn't, observe the resulting drill bit run-out when using your Dremel; you don't want to auger out an elliptical hole in the vent screw.
6. Clamp the steel plate to the drill press table and screw in your vent liner.
7. Dab cutting oil on the screw head and drill as rapidly as you can in order to prevent heat build-up, but just a little too much pressure will snap the tiny bit. Add more oil as you make an impression in the screw head.
If you do it correctly, a .0315" drill bit won't go through the resulting vent liner. Your cost per vent liner can be as low as $0.50, depending on how many liners you produce and how many screws and drill bits you ruin.
Harley
|
|
|
|
Post by Flatland Hunter on May 8, 2008 7:39:44 GMT -5
If you do it correctly, a .0315" drill bit won't go through the resulting vent liner. Thanks for all the info! What did you mean here? "Won't go through", did you mean vent hole diameter wise? I took it as that... just making sure. And everything else is as I thought but wanted to dbl check. Thanks again! |
|
|
|
Post by Harley on May 8, 2008 7:46:30 GMT -5
First, I made a mistake in typing the drill and tap set # (since corrected).
Yes, I mean after you drill the screw you should not be able to push a .0315" bit through it. That would mean both that the hole is about .031" and that you didn't drill "out of round".
Harley
|
|
|
|
Post by edge on May 8, 2008 9:32:04 GMT -5
I don't know if folks are still doing this, but a few years ago we were heating up the vent liners with a propane torch to a cherry red and dunking them in an oil quench.
Many felt that this added a fair amount of life to the the vent liner.
edge.
|
|
|
|
Post by Flatland Hunter on May 8, 2008 10:06:26 GMT -5
Well I figure 100 vents, even accounting for the inevitable screw ups, will give me a near lifetime supply even if I replace them after every 30 shots.
Regarding #7... drill as swiftly as possible. I am glad you included that because I would have done the opposite.
|
|
|
|
Post by Harley on May 8, 2008 10:53:24 GMT -5
Robbie, the idea behind drilling swiftly is to prolong the life of the drill bit. It's a fine balance between that and bearing down hard enough to snap the bit.
Edge, this is just off the top of my head (so to speak), but if you heat the vent liner with the torch, then plunge it into oil, isn't that analogous to "annealing" brass, which is a softening process? If this is correct I would expect it to shorten the vent liner life. Again the disclaimer that I'm not sure what I'm talking about.
Harley
|
|
|
|
Post by KerryB on May 8, 2008 10:54:22 GMT -5
I have been away from the computer till now, sorry for the late response. Looks like Harley and Edge covered everything that i would have said! Thanks for covering me guys............  |
|
|
|
Post by edge on May 8, 2008 11:01:19 GMT -5
Harley, Heating and quenching hardens steel...depending on the carbon content.
Copper alloys anneal when heated regardless of how quickly it is cooled. ( By queching you get less scale, but that is really the only reason )
To anneal steel you heat it and cool it slowly.
edge.
|
|
|
|
Post by Flatland Hunter on May 8, 2008 11:04:03 GMT -5
Kerry, just figured I ought to get on the stick if I was going to do it. Had no problems with Grainger or the other site ordering the screws and bits... now I just need to get the other items and get drilling.
|
|
|
|
Post by Harley on May 8, 2008 11:05:46 GMT -5
Thanks, Edge; I'm glad I admitted my ignorance up front.
Harley
|
|
|
|
Post by Flatland Hunter on May 8, 2008 17:08:46 GMT -5
Some have asked where I got the screws... I will repost KerryB's post with that info: Shipping for both ran the total for the orders to $40. |
|
|
|
Post by Flatland Hunter on May 8, 2008 17:11:18 GMT -5
RPM for the Drill Press? Found this from ET... My best current speed at the moment is 840-RPM where my drill bits last the longest. It was touchy at first until I kept an eye on the drill bit and made sure it didn't bend while drilling meaning too much feed pressure was being applied. Ed Anybody have any further advice? |
|
|
|
Post by Harley on May 8, 2008 17:16:31 GMT -5
No more advice (it's not brain surgery), but a note:
Grainger wouldn't sell to me "over the counter"; they insisted they only will sell to a business. My wife is in publishing, so I gave them her business name. They didn't even check it out, just okayed the order. (Hint.)
Harley
|
|
|
|
Post by KerryB on May 8, 2008 17:20:45 GMT -5
I forgot to mention that i lost the original Dremel chuck that i had been using while cleaning my work shop bench and i bought a replacement. The new one doesn't fit properly for some reason and i have been wrapping the bits with a couple of wraps of aluminum air conditioning duct tape to get the chuck to tighten properly. Not a good fix and i am now looking for another properly fitting Dremel chuck  .........................Let us know how you progress with your project? $40 for 100 ventliners is pretty cheap in anybody's book.................... |
|
|
|
Post by Harley on May 8, 2008 17:24:04 GMT -5
KerryB, Dremel makes at least two different sized chucks. I have both of them and neither will tighten enough to hold the micro bits. If you were previously successful with a Dremel chuck, either it's a discontinued size or there's a third size out there. Hope that's the case.
Harley
|
|
|
|
Post by Flatland Hunter on May 8, 2008 17:46:37 GMT -5
Corrected that post to read $40 total (includes shipping) for both the screws and bits...
|
|
|
|
Post by Flatland Hunter on May 8, 2008 17:49:56 GMT -5
With Harley and KB's advice this might be a good Tips & Hints addition...
DONE
|
|
|
|
Post by Flatland Hunter on May 11, 2008 22:47:16 GMT -5
I am wondering... what RPM's do most turn their bits at when drilling vents? I borrowed a press from a friend and it recommends the 3100 rpm setting for the small bits. I have successfully drilled one at that rate but do not want to mess anything up... thanks!!!
|
|
|
|
Post by Flatland Hunter on May 12, 2008 6:56:13 GMT -5
Well, couldn't sleep so I got and drilled some more vents... at 3100 rpm's the bit lasted just one more vent and died on the 3rd. Changed down to 1100 rpm and went 12. On the 12th the initial entry area opened to .032 and was able to move the .032 pin in just a little before it stopped.
So I am thinking bits... are good for about 10 vents at 1100. Next lowest setting is 620 rpm. Unless someone thinks 620 rpm will make the bits last longer I will stick with 1100 rpm.
|
|
|
|
Post by minst7877 on May 12, 2008 10:10:56 GMT -5
Heat on the bit is the killer. Keep a lot of coolant / cutting fluid on it and try them at the next step down to see if it works any better.
DC
|
|
|
|
Post by Flatland Hunter on May 12, 2008 10:37:27 GMT -5
I did not know what to use for fluid so have been using a big dollop of Break Free... read where mineral oil might work well.
|
|
|
|
Post by Flatland Hunter on May 12, 2008 10:38:50 GMT -5
I also do not do it in one stroke I go about 3-4 diameters of the bit deep and then clear it back into the dollop of oil and then back in.
|
|
|
|
Post by E.T. on May 12, 2008 19:59:58 GMT -5
Well, couldn't sleep so I got and drilled some more vents... at 3100 rpm's the bit lasted just one more vent and died on the 3rd. Changed down to 1100 rpm and went 12. On the 12th the initial entry area opened to .032 and was able to move the .032 pin in just a little before it stopped. So I am thinking bits... are good for about 10 vents at 1100. Next lowest setting is 620 rpm. Unless someone thinks 620 rpm will make the bits last longer I will stick with 1100 rpm. Flatlandhunter If you are getting 10 vents with one drill you are doing really well for the hardness you are drilling. At approximately 600RPM I was snapping bits as they seemed to bind a lot easier at the slower speed. Gone are the days of extra expense and waiting for existing quality vents to arrive. Gone are the days of trying to get extra shots on vents because of the cost. Nicely done for a first time go at it.  Ed |
|
|
|
Post by KerryB on May 12, 2008 21:10:48 GMT -5
Well, couldn't sleep so I got and drilled some more vents... at 3100 rpm's the bit lasted just one more vent and died on the 3rd. Changed down to 1100 rpm and went 12. On the 12th the initial entry area opened to .032 and was able to move the .032 pin in just a little before it stopped. So I am thinking bits... are good for about 10 vents at 1100. Next lowest setting is 620 rpm. Unless someone thinks 620 rpm will make the bits last longer I will stick with 1100 rpm. Sounds like you are doing just fine! I would continue with the 1100 rpm if i were you as you are getting optimum results at that speed. It is a very fine line when dealing with drill rpm and down pressure on the bit. Backing the bit out regularly for more oil seems to work well for me too. I am currently out of bits and will be ordering a couple more packs in the next few days. I currently have a new box of 100 Holo-Kromes, so i'm about ready to get going again. Glad these screws and bits are working out for you! I might try the heat treating thing on my next batch as well and see if they last a little longer. They do pretty well as they come from the factory though.................. Keep us posted on your findings since others here can benefit from lessons that you and i pass on! |
|
|
|
Post by Flatland Hunter on May 13, 2008 9:08:56 GMT -5
1100 rpm is definitely the best for this press... tried 620 and it chatters a bit. 1100 is smooth and I have cranked out 11 on a bit and it is still cutting real smooth.
I am separating vents by bit... meaning, grouping vents according to the bit that cut them and will store them that way. Don't know if that will make a difference but manufacturers separate stuff by lot for a reason.
The Break Free seems to be doing well as a cutting fluid so I will continue to use it.
Thanks for all the advice!!
|
|
|
|
Post by richard on May 14, 2008 17:22:16 GMT -5
E.T.
I just picked up three .031" cobalt drill bits from Grainger (@ $3.84 ea.) and thought I would have a go with those 25 screws we got from McMaster Carr earlier this year. I made up a fixture with the 82* taper to hold the screw in correct alignment and below flush with the piece of 1/2" aluminum flat stock. So far I have drilled 17 screws with one bit. (it is still cutting) The first 12 cut right thru the center. The last five came out just slightly off center. I feel as the bit get somewhat dull, it wanders a bit. All the holes are under .032" (my .032 tip cleaner will not enter the hole and my .031" pin gauge goes in just fine) I'm thinking there might be a few .0000" leeway. I also drilled at 1100 rpm and used Rapid Tap cutting fluid.
I think I am going to order a dozen of those drills that Faltlander is using: Bosch! $13 + $7 shipping is a lot cheaper than $3.84 ea ;D. I am also going to get a 100 of the Holo Krome screws. Both those you got and the Holo's are Rockwell C38 to 44. I also used a 3.16" carbide 90* spotting drill to chamfer the end. Yup, it sure beats 4 vents for $28!
Richard
|
|
billc
Eight Pointer
Posts: 164
|
Post by billc on May 14, 2008 17:51:46 GMT -5
McMaster-Carr has cobalt drills 3069a109 $1.98 each for 12 or more. They also have screws 91253a001 $11.20 for a pack of 100. Screws are a minimum C39. Just a thought to save double shipping.
Bill
|
|
|
|
Post by E.T. on May 14, 2008 18:10:12 GMT -5
Richard Looks like you got the vent drilling down pat already. I don’t have a carbide bit for chamfering and just introduce the tip of 3/32 drill by feel for producing a nice chamfer for funneling the flame into the orifice. I agree having the right quality cobalt drill sure makes a difference for the number of vents per drill bit. With the extra money now saved I imagine a few more sabots, bullets and even powder can be bought instead of investing in vent liners. Ed |
|
|
|
Post by richard on May 14, 2008 20:00:17 GMT -5
ET
Have you found that the vent liners with the holes slightly off center cause any accuracy problem? I'm saying that the drill bit exits maybe....the most..... one drill bit off center......the side of the hole touches the center. Again, that was only on the last five (of 17) and probably due to the drill wandering as it got duller on one side.
Richard
|
|
KerryB
.........................Let us know how you progress with your project? $40 for 100 ventliners is pretty cheap in anybody's book....................
