Air Delivery System - I was recently asked about my air delivery system by Hilton Yam. Hilton noticed that I have a Campbell Hausfeld compressor while he was looking at some of the pictures posted here on the site.(he's got good eyes) and he asked how well it worked for my application. I thought that perhaps some of you might also be curious so I decided to post a short description along with some pictures here in this section. I am quite pleased with the way it all worked out, and maybe someone else would like to know a bit about it.
Here is a section of the text that I posted on the forum .......
................"You have good eyes...the compressor that I have is a Campbell Hausefeld contractor grade that delivers 5.3 CFM at 90 PSI. I REALLY LIKE IT !!! It's perfect for what I need and it's so small. The internal tanks are only 4 gallon...so without any external storage you would basically be running full tilt at all times. I added a simple (and cheap) pair of portable 10 gallon air tanks (the kind you air up tires with) they are manifolded together and then all three (the two tanks and the compressor) are fed into a series of PCV pipes that feed my bench. I attached the tanks and the compressor to the PVC with a 4 way manifold and the when quick disconnect fitting on 3 of the 4 holes. this makes it so I can pop the disconnect fitting and take the compressor into the back yard (or across town for that matter) and still have a nice 4 gallon portable system. Try that with a big 25 gallon single unit. I basically just use the contractor compressor as the "engine" behind the rest of the system. The two portable tanks usually stay connected but if I wanted to I could disconnect one or both of them also. It makes for a very nice modular air system and it didn't cost any more than a standard 25 gallon upright rig. I bought mine at Home Depot as a floor model for $199.00 (no box) but I saw them in the store for $275.00 just last week. The portable air tanks cost me 24.95 each and they even have an air gauge on them already. So I have a 27 gallon system now. that's 2 x 10 gallon portable tanks. Plus 4 gallons onboard with the compressor Plus another 2 gallons in the PVC lines for a total of 27 gallons. The compressor only kicked on twice during the sandblasting of the two frames, and pressure never dropped below 90 PSI."........................
Here is a picture of the Compressor that acts as the "engine" for my system. It is marketed as the "Extreme Duty" entry in the Campbell Hausfeld line-up and as such it was built to run continuously like the way a contractor would use it. This model has a cast-iron sleeved piston to make it last longer. I also like it because of it's size. Space is at a high premium in my workshop so smaller is better. Here is another picture so you can see how small it is.
This picture shows a closeup of the 4-way manifold that I wrote about. When I was putting it all together you will notice that I stuck in an extra T-Connector. This is so that I could add yet another 4-way if I ever wanted to increase my storage banks. All I would need to do is unscrew the PVC plug in the bottom and insert another 4-way in it's place.....viola, presto double the capacity. You will also see that I have a main line shut-off ball valve. This allows me to isolate the system and remove the air compressor, without having to drain the tanks. the whole system would still be pressurized and would continue to function even if the compressor is temporarily removed.
Here is a picture of the type of tanks I used. I bought two 10 gallon portable airtanks for 24 bucks each at Home depot. You may notice that in this picture I have an additional 5 Gallon tank hooked up. I had taken one of the 10 gallon ones out to put air in the neighbor kid's bike tires when this picture was taken. By having the quick disconnect fittings on all 3 of my tank whips it allows me to quickly remove one or more of the portable air tanks without draining the system. It also means that I can simply click in all 3 of them for added air storage if I need it.(32 Gallons) Or I can use one of the whips to feed my Beadblaster or anything else that I need air to. This picture shows the spare whip hanging ready for use. I just click it in to the beadblaster when I want to blast.
The whole system is just a bunch of PVC pipe and fittings that feed this Bench air control panel (homemade out of PVC and air fittings) I decided to put two quick connect fitting by the bench. This allows me to run two air tools at once....or to have low and a high pressure going at the same time. I put a regulator and an air filter/dryer on the lower feed so that I could use it for painting or even airbrushing. The top one is high pressure only.(straight off the tanks). The short section of pipe between the two ends (the one with black tape on it) is only to add rigidity it DOES NOT connect the two pipes.
That's about it is a nutshell.....It really makes for a flexible system. Every piece is portable, it can all be moved around easily, and it costs about the same as an upright 25 gallon system. But mine is much more configurable.....hehehehe If I run out of space I can even put the compressor in the attic and just run a hose down to the line-in connection. All parts, fittings, pipe etc..are available at Home Depot. I already had the system long before I started this project so I don't have the receipts but I think it was around $350.00 for the whole lock stock and barrel.....including all the nickel and dime stuff.
Grizzly Mini-Mill - When I finally decided to take the plunge and start doing some "serious" home gunsmithing, the most pressing question I had was whether or not the new "Mini-Mills" that are popping up would have enough power to do what I needed one to do. I tried posting the question to all the forums I could find. I tried calling the folks at Brownells. I even called Grizzly. The bottom line was always the same.......we don't know for sure. Most of the answers I got from the forums were pretty much the same. Everyone said to save up my money and buy a Bridgeport. Well sure, but that doesn't answer my question. The question wasn't "will a Bridgeport work or not" it was "will a mini-mill work or not".....the truth is, nobody had tried it, so they couldn't say for sure. That meant that I would have to be the one to lay out the cash just to find out. Now don't get me wrong here, I would LOVE to have a Bridgeport.....but I don't have the space for one, and I didn't want to spend that kind of money. I wasn't sure just how much use I would get out of a mill so I didn't want to sink several thousand bucks into one just to "Play" with my guns. The other big factor like I already mentioned is space. I have a very small corner of the garage, all my "gunsmithing Crap" (as my wife calls it) will need to fit in that space. A full sized milling machine would pretty much dominate the whole area, and leave me with no room for anything else. My wife absolutely insisted that we had to be able to put both of our vehicles in the garage. We both own full sized SUV's so this is no small task. Everything had to be arranged to fit flat against the walls. Here is a picture of the Workshop as it exists today. Notice the way everything is arranged. I have to move the stool when I pull my truck in. The front bumper comes forward to about where the stool is in the picture.
OK.....so now you know why I was so interested in finding out if these little "garage sized" mills would work for my gunsmithing. If it actually does perform all that I need it to do, then it is a better choice (at least for me) than a full sized mill. And at less than $500.00 brand new, I can justify the expense. Remember that the mill also acts as a precision drill press. I do not need another machine for drilling, and since I didn't already have a press this kills two birds with one stone.
The following section explains about the machine as well as some other thoughts I have about using the Griz for gunsmithing....if you get bored easy you should probably skip this whole write-up, because as usual I get pretty long-winded. Also, if you are familiar with milling operations already....then you are gonna laugh your ass off at this. I am well aware of the fact that the axis all have proper names. But to put it bluntly I don't care. It confuses me and makes my head hurt. So I use MY terms and they are: Front/back.....left/right.....and up/down. That just makes a lot more sense to me, since I'm just a home smith newbie......on with the show.
The Griz in a box - I figure the best place to start is to show you the picture that Grizzly Industrial uses to market this machine. In this picture you will see the overall machine as well as a good illustration on how the head and column tilt 45 degrees to either side.
I was surprised by all the accessories that were included with the mill. I like the fact that Grizzly gives you all the tools and collets that you would need to start milling right out of the box (except end mills). This picture shows what came with the machine. It came with all the wrenches and allen keys for every nut and bolt on the machine. It also came with: 2 T-Nuts, a 3/8" collet, a 1/2" collet, a Drill chuck adapter w/key , a draw bar, a quill stop, a head stop (not shown) and a small plastic oil can. The manual was also included but I didn't take a picture of it.
Operating the Mill - Here are a few pictures that show the Front , Left, and Right side of the mill. I have never operated a mill before so I was a bit worried about how hard it was going to be to learn all the controls and feed mechanisms. I shouldn't have worried at all, it was easy to pick it up in a few hours. This machine is completely capable of maintaining .001 tolerances on any piece that I have works with so far. HOWEVER......I would strongly recommend to you that you do not try using the stupid little ruler scales for doing any fine detailed cuts. Every axis (X,Y and Z) has a scale on it. I guess they figure if you don't have any other way to measure movement then you can use the scales. The scales look like little rulers (kinda like a measuring tape stuck to the side of the machine). Here this picture shows one of the goofy little scales. Yeah Right !!! I'm gonna trust my beautiful custom Sistema to that thing......wrong.(more on this later).
Before I get into the proper way to do precision cuts, it might help if you could see how the "micro feed" works on this little baby. If you looked at the Right side picture again closely you will notice that it has a 3 bar handwheel on it that looks and works just like the handweel on a drill press. This moves the head up and down the column in rapid fashion. It allows you to quickly move your depth to about the general area that you want. But this handwheel has an additional worm gear that when engaged will allow you to move the head up and down by .001 increments (and even fractions thereof). The way the worm gear works is by pushing in or pulling out the handle of the handwheel. This picture shows the little label on the side of the machine to illustrate. To help you visualize it better here is a picture of the handwheel when the finefeed is NOT enabled (regular mode). And if you push the handle in towards the machine this picture shows the finefeed engaged and ready for micro adjustments. Once you engage the finefeed, you no longer use the big bulky handwheel to move the head, now you use a small knob on the front of the machine. The knob makes it easy to make very tiny adjustments. This picture shows the finefeed knob I'm talking about. Yep you guessed it....it has a goofy little scale on it too...hahaha.
Now that I've explained how to move the head up and down, the right/left and front/back parts are super simple. Look again at the front view picture and you will see two round black handwheels. One on the front of the machine and one on the right side. These simply move the table either to the left/right or front/back. They do not need a finefeed engagement because they already are. It takes one full turn of either wheel to move 1/16".....so just turn it a little bit and you move a little bit. Pretty simple.
Getting precise - Alright, so you may be wondering why I keep making fun of the little scales that are pasted all over the machine. Here's why..........they suck ! Hahaha...well they do. The scales just aren't accurate enough for me. And the little hash-marks on the handwheels are too confusing. The hash-marks are all in metric thread conversions. And to make it even worse they are all different from each other. This picture shows a closeup of the front/back handwheel, it's marks are in 1/62 revolutions. This picture shows the left/right handwheels hash marks and it reads 1/48. Don't even get me started on the downfeed hashmarks. So basically I just ignore them all together. I use Dial indicators instead. They are super easy to read (even for an amateur like me) and they have fantastic precision.
I made the dovetail sight cuts and they came out with .000 tolerances (meaning that they were so exact they didn't register on my gauges). Here is how I use the dial indicators.... I get the workpiece mounted in the milling vise and then get the cutter positioned at a point that I want to start measuring from. (like aligned with the front of the slide for example). Then a place the dial indicator so that the tip of it touches the milling table (this is for front/back or for side/side). This picture shows the dial indicator set-up and positioned to measure a right to left cut. As the table moves, it registers on the dial face and reads out in big bold .001 increments that are easy to understand. To do up/down precision measurements I use another dial indicator. This one just uses a magnet mount that I stick on the column. Here is a picture of the up/down indicator. The tip simply touches the head assembly and moves as the head moves.
Recommended accessories - I don't have a whole lot of extensive milling tools, and quite frankly I haven't needed them either. As of today, I have already done the following modifications using only the tools that came with the machine and the ones listed here:
Lower Ejection ports
Cut front cocking serrations
Bevel magazine well
Install custom dovetail sights
I have no doubt that there are other accessories that would make life easy, but this is all I need for now. Here is a picture of the measuring equipment that I used. All I have is a simple dial caliper, and a set of outside micrometers. ** NOTE ** I would like to pick-up a depth micrometer in the future, I think I will use it. This picture shows the endmills that I have. I just bought a cheap HSS 4 flute set from wholesale tool to get me started....but I have added 3 others that were needed. (a carbide 3/8", a .290 x 60 degree dovetail cutter, and a 45 degree 1/2" countersink) So with the basic set plus those three others you would be all set (for now).
Limitations - The only limitation I have found has been with the table travel. It is not a big deal at all....but to be fair I should mention it. The problem is that the table does not have enough travel from front to back, to be able to make front cocking serrations the "conventional way". The cocking serrations are the ONLY operation that I have performed that caused this to happen. Here's the deal......if you use a Yavapai slide jig (which I recommend), then the "offset" that is created by using the jig eats up all your front/back travel adjustment. Understand that the table only has about 4 inches of front/back travel to begin with. These pictures are worth a thousand words. The first picture shows the area you can reach with the cutter when you have the jig mounted forward. The second picture shows you the problem you have if you reverse the jig. the slide would be too far away from the cutter to reach it.
In a "conventional" serration cut. You would set the mill head at 20 degrees to one side. Make your cut. Then tilt the head 20 degrees to the opposite side and leave the jig in the vise. You just loosen it, remove it, and then slide it back on the jig from the other direction....simple huh? You retain all your leveling on the workpiece in the vise and you shouldn't need to reset it (just check it). But this method requires you to run the table to the opposite end and the opposite corner of where it was just located. (about 6 inches). The table only has 4 inches so it won't work like that.
With the mini-mill you need to do it a little different. You do the first cut the same as with any other mill. However....on the second cut you DO NOT tilt the head to the opposite direction. Instead you remove the jig from the vise. Turn the slide around so the other side is facing up, and then re-level the jig in the vise....but this time when you put the jig in (before you tighten it) you have to slide it as far as it'll go to the opposite side of the vise.(it'll still grip don't worry)
In all fairness....I should point out that this whole long winded example is a non-issue if you put the slide directly into the vise instead of using the jig. It has plenty of travel to do both sides if you do it that way. Also I want to point out that the left/right travel is not a problem at all. You have nearly 10 inches of travel on that axis.
I have experienced absolutely no problems at all with the horsepower. The motor on this thing is more than enough to handle the jobs I've thrown at it. Goes through like butter. Just use a nice slow feed rate and you'll go through just about anything. (be sure to use carbide cutters though when you cut hardened stuff......but that's true with any mill).
Final Word - Well, I finally have the answer to my original question.
"Will a mini-mill do the job for a home smith?" The answer is YES ! I have no problem at all recommending this little brute to anyone that has the desire to do home milling on small parts and handguns. All this for under $500.00 and it even fits on my bench. The wife is happy...........
For more Information about Mini-Mill Set-up and Measuring details check the Notebook section.