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I give up, whats the secret to getting more than one notch per week. I have a 1 5/8" Morse holesaw connected to my floor standing drill press on the almost highest speed and the @#$%^%^&&*thing still locks up and jerks the tube out of kilter....some of the ads for others show them being used with a electric drill...this I have to see...my 1 hp drill press wont work..
Are you using any coolant on the pipe? If not, chances are it will heat as you drill & work harden as you go, making it harder to drill, the deeper you go.
Last edited by Stephen; 08-27-2009 at 11:04 PM.
Reason: typo
A "little cutting fluid", or a continuous stream taking away any heat trying to build up?
When I worked in a CNC machine shop, ours was a continuous stream of fluid, being pumped & recycled through a tank. I'm just wondering if all your really achieving is, heating up of the cutting fluid your adding. The amount of pressure shouldn't take much, if you have a good blade/bit & a cool temperature of the material. And if it hardened already, then work hardened even more.....
Both Stephen's at the same time...i'm honored..i'll try to not get you mixed up....
I did the angle grinder thing for a couple of copes but a racer friend of mine said that the NHRA tech boys might not be impressed. I messed up my share of tubes before I got it looking okay....
So I'm thinking the cordless drill and notching tubing thing is a less than accurate sales gimmick?
If you're going to TIG everything together then a good tubing notcher should be used to reduce the size of any gaps. A good welder with MIG can easily fill in any gaps.
I won't know how good the welds really are until I go in for a chassis certification next spring. I can't see any of them failing. You don't need to center notch the tube. In other words, the notch doesn't need to be deep enough to go half way around the tube. It just needs to be notched enough so that the tube can be welded all the way around with as little gap as possible.
It didn't take very long to find my link on installing the cage. You can see how much some of the tubes are notched.
So I'm thinking the cordless drill and notching tubing thing is a less than accurate sales gimmick?
Seems to work ok for me. Just as long as the fit is good, really shouldn't matter what you use to get it to that point. One of the top chassis guys in the area uses a bench grinder on a pedestal that he moves over by whatever he's working on. Grinds on the tube a bit, checks the fit, grinds some more and so on then TIG welds everything together.
A good fixture like pictured above is almost a requirement for drill notching tubes.
I more often use my chop saw; just cut two 45's so that the end of the pipe is pointed, the grind the points down a little bit with a 4" disc. When doing even sized pipes, you can quickly figure out perfect fitment, and it leaves you a nice back cut("v") to weld into. - If the pipes are coming in at a different angle than 90 to each other, you simply cut what will be the top 45 back further.
I'm not finding any direct pics on my photobucket, but you can kinda see some in these:
Stephen, the rpm of the drill press is at 1600....do you think it needs more or less?
You're spinning the holesaw way too fast. Without knowing the type of tube/pipe you are notching or the thickness I would recommend slowing the drillpress down to about 250 rpm and trying it again.
You should probably go buy a new holesaw first though, as you likely ruined the one you have been using.
You're spinning the holesaw way too fast. Without knowing the type of tube/pipe you are notching or the thickness I would recommend slowing the drillpress down to about 250 rpm and trying it again.
You should probably go buy a new holesaw first though, as you likely ruined the one you have been using.
I thought I was spinning it to slow actually...I did try it at the slowest speed (400rpm)and the jerking actually was worse. When I sped it up a little the cuts were smoother. As I sped it up more the smoother it got. I also changed the holesaw twice thinking that I had damaged the first one, but it wasn't much better. The tubing is 1 5/8 x .134 mild steel
First thing I thought was it was too fast. I have two drills at work. The little one will spin up to 1500rpm. The big drill (pneumatic) will drill anything, at about 400-600 rpm. Ive never got it stuck, and its 1/2 hp.
Ive found the harder the material, the slower it needs to spin. If Im drilling, or cutting aluminum, it doesnt really matter. Chromoly, or stainless, I go slow.
holesaws really have too course teeth for the job, and that's why you're having problems, but that being said, you should use the lowest rpm you can, I usually use 250rpm on my drill press if I use them. I also have a Bridgeport and have done it by just plunging a flycutter, endmill or even a boring bar set to the diameter of the tube.... (after cutting a perfect notch I'll take it and put it up against the belt sander to quickly bevel the outside edge to give a place for the weld to sit, making the final joint/weld pretty)
All that being said, I only do that when I'm screwing around/have time (the last time was when I made "protective custody enclosures" for the tomato plants this year using welded conduit, the thin wall really needed tight fitting joints and I was screwing around). I don't think I've ever cut all the notches on a cage or rollbar with any of these, I usually just cut it off with a bandsaw and then notch it with a 4-1/2" angle grinder by hand (you can actually use either a cutting wheel or a grinding wheel, they both work fine). The first few I draw myself a pattern to follow with a marker, but after doing a few you get to the point where you can whip them out pretty fast without any guide. Keep the joints tight and you shouldn't have any problems with TIGing or with tech.
The fastest way to get a good notch is probably using a chop saw or anything that will do a straight cut at an angle... something around 30* cut off both sides works well, for exact angles (taken from a post on pirate 4x4, but you'll find it all over, even with pictures...):
Quote:
The chop saw method, if understood, is a science. With known tube size and joint angle, tube can be notched with great accuracy. The notch is achieved by cutting two opposing angles on one end of a piece of tube, to form a point. The cross-section of this cut will be an elliptical cut due to the shape of the tube. Changes in both of the two angled cuts must be made for the intersection angle and the size of the two tubes being joined. The only real limitation is the max angle of the chop saw.
You start with what I call the base angle. This is the angle of both cuts if the joint was 90*. For an example, I am fitting Two tubes together that are both 1.75", at an 90* joint. The base angle, or the angle of both cuts is 28*. These two cuts must meet at a point, and the point must also be centered on the tube.
Remember your base angle will change with the tube being cut and the tube that you are fitting to.
Here are a few examples of base angles...
2.0" to 2.0" tube, base angle of 30*
1.75" to 1.75" tube, base angle of 28*
1.5" to 1.5" tube, base angle of 26*
1.25" to 1.25" tube, base angle of 22.5*
1" to 1" tube, Base angle of 20*
Now to fit different size tubes together
1.75" to 2" tube, base angle of 25*
1.75" to 1.25" tube, base angle of 45*
1.25" to 1.75 tube, base angle of 20*
1" to 2" tube, base angle of 12*
What if instead of a "T" joint, I want the notched tube at a 15* angle with my first 1.75" tube???? You must start with your base angle, which was 28* for 1.75"(remember above), and subtract 15* from one cut, and add 15* to the other cut to form a perfect notch. So now I must make a 13* cut and an 43* cut with the point centered on the tube. Perfect coped joint, with no grinding.
I mount the tube in a vice and use a 90 deg grinder with a 3/32" thick wheel. I can rough it out in 4 cuts, fit the tube, then I'll usually have to trim the length a little or the angle of twist. Put the piece of paper back on the tube and remark. Cut if it is way off, or put a thicker wheel on and grind.
That's some massive cage with lots of extra tubes. Are all the main tubes made from 1-3/4" tubing?
I would guess from the cage pic and his avatar pic, that it's more SCCA/NSA spec cage for a handling car. They have more requirements than us straight line guys.
Shagwell is correct, It is built to the NASA and SCCA rulebook.
The biggest difference between them and the NHRA / IHRA rules is the main hoom diagonal, which IMO is a way better than having those little supports that go down to the trans tunnel.
Quote:
Originally Posted by Stephen 87 IROC
That's some massive cage with lots of extra tubes. Are all the main tubes made from 1-3/4" tubing?
All the tubes that are required by the rules are 1.75x0.095 DOM since I will be <3000 lbs. Most everything else is 0.065" wall, in either 1.75, 1.5, or 1.25" OD.
There will be a few more bars added. It isn't done yet.
Shagwell is correct, It is built to the NASA and SCCA rulebook.
The biggest difference between them and the NHRA / IHRA rules is the main hoom diagonal, which IMO is a way better than having those little supports that go down to the trans tunnel.
Plus, we have the kicker legs coming from the main hoop/croos pipe down to the main frame rails, and a funny car cage for anything 25.5 cert or better.
Chassis stiffness is more for important for RR than Drag since we need traction on all 4 wheels. Plus, likelyhood of an accident is greater. Those are the 2 big reasons for my extra tubing.
I'm also going to drive the car on the street, so I made it a priority to push the tubing 'outward' as much as possible to maximize head room. The cage didn't do you much good if you crack your skull on it.
i used simple 4" grinder, sawzaw, and air cutter for mine... took awhile to get the angles/knotches... i would def get a tubing knotcher if i had the money and was gona do more than one cage/roll bar. what scared me was how much i had to grind off for clearance from the door bar swing out kit
i used simple 4" grinder, sawzaw, and air cutter for mine... took awhile to get the angles/knotches... i would def get a tubing knotcher if i had the money and was gona do more than one cage/roll bar. what scared me was how much i had to grind off for clearance from the door bar swing out kit
I have a good notching jig as well as some good holesaws for using with it; that said I still do 95% of my notching with the chop saw.
