How to Notch Tubes

Transcript

- Welcome to today's webinar which focuses on the process of notching round tube. Round tube is a prevalent material used in motorsport fabrication and we usually don't have to look very hard to find it. Things like roll cages, chassis, motorcycle frames and support structures all make use of round tube for its strength to weight benefits. Joining tube together can be a tricky process. The angles and intersect points can be a little difficult to understand but with some planning and preparation, we can achieve some great results using relatively simple cutting methods.

This intersection point will require us to perform a notch which is sometimes known as a mitre, cope or fishmouth in our tube. Cutting this notch can be achieved by using a few different methods and that's what we'll focus on in today's webinar. The first method I want to look at is the paper template method. As its name suggests, the paper template method of notching uses a printed template that we mark back onto our tube to perform a notch. But before I go any further, we need to understand both the physical size of the tubes we are working with and the angle that these will intersect on each other.

If we head over to my laptop here I have the blocklayer.com tube notching calculator page open and this is a free website that is easy to use. If we know the size of our tube then we can go ahead and input these into our calculator and if you don't then you will need to use a vernier calliper to measure the outside diameter and inside diameter to work out the wall thickness. The parent tube is the tube you are fitting up against and the cut tube is the one you're looking to notch. So let's go ahead and measure what we're working with here. And in this example I've just put together what would traditionally be a door bar setup, so we're putting a cross in here with a series of notches that will make up our tube intersect points.

So to measure the diameter of the tube I like to use a vernier calliper as I mentioned and it looks a little something like this, this is a digital version that we can simply switch on and measure our tube. So what I'm working with here, this would traditionally be the B pillar tube and this the A pillar tube. So this will run down from the driver's foot well and terminate into the floor and this will be behind the driver's seat looking on the side of the car. So traditionally a B pillar, at least here in Australia and New Zealand is 1.75 and I know that and I can verify that by measuring it with my vernier calipers here. So 1.75 metric measures 44.5 and I know that this is a 2.6 mm wall thickness so I can go ahead and put that as my parent tube diameter as we're fitting up against that into the calculator.

So here we have a little slide bar that we can adjust and basically we're looking for 1.75 inches which we're nearing on now, there we go 1.75 inches for our parent tube diameter. And then our cut tube diameter which is the one that's heading from the top here down to the bottom is 1.5 inch which I can measure that. So 38 mm in metric. And you can actually change the tubing calculator into metric or inches if you choose or you can just scroll down here, 1.5 inch. So that is our cut tube diameter and then that's it for that.

Now we just need to find the angle. So to do that, with those dimensions added into the calculator, we just need one more variable and that's finding the angle of our intersecting tubes. This requires us to understand where the tube is going to sit and because we haven't notched it yet then this can be tricky to work out. We can use a straight edge ruler, a string line a tape or a scrap piece of steel and we can sit it in position and measure the intersecting angle by using an angle gauge, protractor or even a digital angle finder like my bevel box. If you haven't cut your tube yet then it's a great time to do it as well.

This is, to use this angle to understand the start and the end point of your tube. Remember that notching the tube will essentially wrap it around the parent tube so we need to allow enough material to do so. I like to them add 20 mm onto each end to allow for the notch to be cut. Now I've already cut my tube but I'll show you how I find that. So I mentioned that we need to know where our tube's going to start and end so I'll take this little magnet off here.

And I mentioned that I want my full tube to be able to run from the bottom of the B pillar main hoop up to the A pillar so a really good way of just finding out this angle is using some tape or a string line. So I'll go ahead and measure with some tape. So what I like to do is come from here which is the top section of the tube up to my top mark where I know that my A pillar door bar is going to run through here. And then using a tape measure, this is to find the actual length of the cut tube, I go from the centre of my tube to the centre of here. So I have 1065 mm in that which I've actually pre cut my tube to suit that so now once we understand that we need to input our dimension, our final cut tube angle into our calculator to ascertain our printable template.

So how I do that is I mentioned before there's some digital versions but the easiest way is to use a small angle finder and this is a fairly cheap little tool and again it's digital. And it'll allow us to find our notch angle. Just always make sure that you zero it in the zero position. So now we can run down here, sit it up against our tube and measure our tape. So this is a smaller version, there are longer ones that you can do or longer versions that you can do and also we can find this via a magnetic angle finder, something like this sitting it up against our B pillar tube and then onto our tape or onto our dummy bar just to understand the intersecting angle of those.

Which is 65° so that's already keyed into my chart here but you can see how the different angles or the different cut tube angles actually affect the notch size. So once we drop it right down the notch becomes a lot longer and this is what I love about the paper template method, we can really understand quite easily without cutting tube the actual length and orientation of our notch. So once you're happy with your desired angle and length then you can input it into the template to give you a really good understanding of how that is going to sit and again by using tape or a string line then that'll be really handy. So now we have a visual of what our notch is and an angle in our calculator. So once the template's complete we just need to print it out and stick it to our tube.

So just make sure that your printing default settings do not change the scale of the downloaded PDF as we need that to be 100% to actually reference exactly what our notch is going to look like. If your printer tries to fit it to paper then it may not actually wrap around the tube and be the right length. So with it printed out, we can now cut it to shape and wrap it around the tube and it's a great idea to add two reference lines marking the top of the tube and the bottom of the tube. This will allow us to easily clock the tube in the right direction for our second notch. So I've got some printed out templates here and I've just outlined this a little darker so that you can see but it has all our dimensions listed and once it's cut out, it looks a little something like this and then once it's wrapped around the tube, it will neatly actually tell you the notch diameter and the profile of that and we can mark that back onto our tube and cut it out.

So once that is marked back onto the tube all we need to do is mark it back with a permanent marker and cut the notch out which I've already done on this piece. So how I've done that, there's a few different ways you can do it, you could use a chop saw or a buzz saw but I like to use my cordless angle grinder. In two variations so I have one set up to cut the rough sections of tube out and then I have another one for grinding them. So here I'll usually rough cut the sections of material that I don't need off with a 1 mm cutting disc. Just make sure that you're not side loading this disc because they are quite brittle and can easily break off but these are really good for cutting the excess material away from the notch and just try and get them close to your marks so that you don't have to do too much grinding.

There are different cutting wheels for different materials but those 1 mm cutting discs do a great job in steel. And then my weapon of choice for being able to notch tubes is via this polyfan curve wheel. As you can see here it's actually got a curved wheel with more abrasives on the back side so you can actually use both sides of the wheel. Being curved, it won't dig into the notch so that we can get it into position quite easily and be able to produce a really clean notch with a polyfan disc wheel like this. You'll see here that it's starting to wear away a little bit and that's just a feature of one of these tools, they actually wear away and once they do they expose another section underneath, another flapper disc and it'll actually continue to cut so you'll get a long life out of these.

They are quite expensive but they do last a long time. So as I said I've previously done that, nobody wants to sit here and listen to me grinding for half an hour so above here you can see, so this is the paper template, slipped onto the tube. And I mentioned before about the centreline marks. So this is top and bottom, so this references both the top and the bottom of the tube and how I've done that is through this nifty little tool which is actually 3D printed. This is from Centurial Tools.

So what this does, it has an adjustable little arm here so this will sit on a flat base, the sharpie pen that sits within it is actually adjustable and this will slide along the tube face and with that clamped in position, I can just make a mark and understand the rotation of the tube. So you don't have to have a tool like this, you can literally sit your pen on something that's half the height or, the centre of the pen is half the height of the tube and be able to get these lines put on. So with that done, we can fit this tube into position. Like I said before, this is a 1.75 parent diameter and then this is 1.5 So we have some specific differences in our ends here. And this will simply fit into our top and bottom marks, let me take the tape off here now.

And throw that away. And then I have a little magnet here, you can never have too many magnets in fabrication and I've got these nice little tube magnets which again are 3D printed items by Centurial Tools and they come in really handy for being able to sit your tube in position. So I'll just whack one under this edge here. Just sit that up on there at our top height and our bottom height. So those are fitting up perfect there.

Like I said before it can be quite difficult to find the actual length of your tube but in doing some measurements you should get it pretty close and then by grinding them into position you can perfect it with a grinder. So as you can see, the paper template method does become a little time consuming and as you start to understand notch angles you probably won't use it all that often. It's a great way to learn about the specific shape of a notch and what you need to do to make them perfectly. A close to perfect fitting notch really makes a big difference when it comes to welding because our weld seam is red hot, it creates a lot of expansion and contraction and if our tube's butting up against our parent tube then it's less likely to move around and you'll have more of a chance of creating dimensionally perfect parts with the right notch. The next notching method we will look at is the tube notching tool.

These come in a bunch of different styles but essentially they all do the exact same thing. By utilising a saddle clamp to securely mount the tube into a hole saw, into a saddle clamp into a hole saw mounted to an arbour inside a bearing, we can adjust the tube notcher through a range of angles before clamping it up and drilling our notch. It's important to note the range of angle that these can cut. Some will go from 90-45° whilst others can go right down to as little as 10° for the intersecting angle. For these tighter angles we will need to use a deep throat hole saw that allows a deeper cut than the regular hole saws.

Whilst we are on the subject of hole saws there are a few different variations available to us in teeth profile and I'll show you these now. So these are both shallow throat hole saws, something that is traditional and can be found at your local hardware stores. I mentioned about the different teeth per inch or TPI, so this is actually a very fine TPI hole saw and then this is a coarse one. So you can see there on the camera, this is actually loaded with wax at the moment which is difficult to see and I'll get to that in a minute but these aggressive ones are really good for mild steel and thicker materials, whilst these smaller TPI hole saws are great for thinner tube as they don't grab and try and tear at them as much but as long as you buy a quality hole saw then it should last a lot longer than those really cheap ones. And again if you need a deep throat hole saw then they are available and they usually are motorsport specific for the use of a tube notcher which I'll show you right now.

So this is your run of the mill tube notching tool. And as I said before this is the angle that we can clamp our tube into and then adjust and the saddle actually clamps different diameter tubes so this is the length of this is actually worked out so that it's central to the hole saw and that hole saw doesn't have a drill in the middle like they usually would because obviously it would, it doesn't need it because it's run in an arbour. So this arbour is inside a bearing and it just has a retaining pin in it at the moment. You can use these in a pedestal drill or a cordless drill but a really handy tool. We actually supply you with the plans to build your own in our Motorsport Fabrication Fundamentals course.

So this is something that I've been using a lot of lately, especially to build roll cages and chassis and it's a great tool when you understand and know the actual notch angle. So it's also important to note that most hole saws don't cut perfectly true. A slight wobble in the arbour will make your notch oversize and I always recommend giving yourself a few millimetres so that you can file your notch into position. It's also important to rotate your hole saw on a slow speed. If you have a cordless drill like mine then I suggest running it at the slowest speed possible and these usually have a two or three speed gearbox so always run it on the slowest speed possible.

This will further improve the life of the hole saw and if you add some cutting wax or lube it'll make life easier on the hole saw and it'll make it last a long longer. Actually got some cutting way here. So this is my go to for all material cutting, aluminium, steel and everything else. This is multi purpose lubrication wax and as its name suggests, it's just a bar of wax that you can load up the teeth with prior to cutting and as it heats up it turns into a liquid and it actually cools down and gives the teeth on the hole saw a bit of a break. Without breaking them, obviously this is important when cutting harder steels like chromoly as the heat in the operation can quickly wear the teeth on the saw.

The great thing about tube notching tools like this is that it completes a notch that's almost ready for fitup straight away. This is after you remove and bevel the outside edge with a grinder or linisher and clean any contaminants from the inside of the tube. Generally if we are TIG welding the tube, we need a smaller bevel on the edge of the notch to make sure the edges aren't too thin or if we are MIG welding the notch then we want to have an even amount of wall thickness around the perimeter of the notch, making the weld uniform as we don't have a whole lot of control over our MIG welder. So I've got my second tube that it going to create the X in our door bar. And this is one that is fresh off the notcher.

Again I didn't want you to sit through the incredible noise that these things make so this is one that I've prepared earlier. So as you can see here, this is fresh off the hole saw and it does actually have a few little burrs and bits and pieces around it and an incredibly sharp edge as you can see here. So we're just going to grab the grinder now and take this down and just clean it up a little and I'll show you the bevel once we've completed. So bear with me while I clean this up. It's always important to wear your PPE, I like to wear my goggles, ear protection and gloves and I'm just going to use my grinder with the polyfan wheel and we'll get this one cleaned up and put it into position.

Give it a couple of revs to make sure it's running alright. Yep we're all good. Alright sorry about the noise for everybody using earphones at home. Get this PPE off and I'll show you that clean up. So I spoke before about the importance of getting rid of the sharp edge.

Once I've got these off I'll be able to show you that. So the sharp edge, I'm talking about sits on this leading edge here and usually when we're using a notching tool like this as the notcher's tearing through the material, you'll start to push away the edges of the tube and this will become really thin and sometimes we need to actually remove quite a lot of this area to bring it back to a weldable state. So this is the small bevel that I've just put on here, so this is something that you would want to TIG weld and the reason we do that is because again if this material edge is really thin and we go to weld it, we'll be welding around the outside and this will be burning away very very quickly and may be contaminated as well and then our weld ends up being a little larger than it needs to be in that area. And this can kind of look a little bit out of place in a really neat roll cage setup or chassis structure. So that's cleaned up and usually what I like to do is always give that area a bit of a scrub with scotch brite.

So what this does is it takes off any of the pen marks or any of the rust or oils or anything that's on the tube from the cutting process and it'll give you a nice clean uniform finish that is ready for welding so we'd usually give this a little bit of a wipe down with acetone prior to welding but here it should fit into position and again I'll use another magnet to sit that where it needs to be. And we're 3/4 of the way through our door bar install here. So usually when we're putting in these tubes, it's difficult to work out the actual length of the top and the bottom. I almost never get it done in one go and that's something that is kind of in relation to making this straight through. So you want to grab a straight edge and make sure that this actual tube looks exactly like this one.

If these are offset at all or this one's slightly longer than it needs to be, then these actual x's won't meet up perfectly and that's always something that I look for in a really neat rollcage install is just making sure that you can't tell which one is the actual solid tube or which one is the broken one. And that sometimes has to do with actually eyeing in the notch and making sure that the lengths are exactly perfect. And there's no real solution to doing that, it's more just getting it into position and working it into place. So with our final method of nothing, we're going to speak about eyeing in the notch. So this is really about grabbing a permanent marker, a grinder and just going at the high point, so basically how we usually do this is, and this can be something that a lot of experienced fabricators may just be their go to method of notching, they might not bother with the paper template method, they might not even have a notching tool.

They might just eye in the notch all the time because as you do it more and more, you start to become in tune with the material and you'll understand what it needs to be able to fit nicely. So here if we were fitting this in, we would just measure, or this would be sitting up here and it may be a little low, it might be sitting down here. And then we just run around with our pen and get it to fit perfectly against the other tube, so any high sections we'd mark and then be able to continue the grinding in those areas to get the tube fitting in nice and smoothly. Another way to do this is to actually use a tube tracing tool. So this is what a tube tracing tool, and again this is a Centurial Tools product.

These are available from many motorsport fabrication wholesalers and I think Pipemaster is another brand that do these. These can be really handy for all sorts of different notches but how they work is basically this will slip over your tube, this side, this will slip over your tube and be a really nice neat fit and if you're notching up against a parent tube then you can slide the template or the notch tracing tool up and then be able to trace that back onto your tube to give you the profile that the notch needs to be. This is similar to the paper notching method but you really don't have to measure the notch, you can just sit a bit of dummy tube into position, making sure that your angle's right, using this tracing tool, you can then set it up, slide it back, trace around and then you'll be eyeing in the notch from that point on. It doesn't give you a perfect notch straight away, it will usually just get you in the ballpark and then you can use your grinder to get it even closer and then perfect it maybe with a file. So on that point of filing, let me just show you a file that I use a lot for notching.

So this is a half round file, you'll see it has a flat section here and then a half round on the back side. So using one of these is a really good way to get a close to perfect notch perfect. So these are not great for removing a lot of material but they are great for just getting in and smoothing the notch out slowly. Sometimes a grinder, if you're using a buffing wheel that doesn't have a nice curved edge like my polyfan wheel, it can dig into the tube a little bit and leave some low spots. With one of these you can iron those out and get them nice and perfect.

So for our final tube we're going to fit this Into position and see how our door bar install looks. So I've just got a little zip tie on the bottom edge here and getting your tubes into position can either be a process of using magnets, zip ties, someone else's arms, a friend's help or many other methods. But usually magnets are the best. Just keep in mind that a magnet actually loses its magnetism when welding so when you're doing this, make sure that you're only tacking with the magnet instead of completely welding. And another thing to note when you're producing tube work for TIG welding especially is that you'll need to drill some small holes so that you create a vent in the tube because as we're welding you'll actually be heating up the air inside of it which is expanding and then as we get to our final area of the weld, all of the air inside the tube's trying to escape somewhere and it's usually the molten weld pool that will force out and actually contaminate the tungsten and you'll have to go back to the grinder, grind the tungsten and in that time that air would have normalised inside the tube and then you can fill the hole.

But it's a great idea to just use a little 3 mm drill, something like this to drill a simple little vent hole inside the tube before you weld over it. So that's basically our process of notching. We've run through a lot of different notches. One thing I will just touch on before we finish up is compound angles and this is another, sorry compound notches. This is another area where our notch tracing tool can come in really handy.

If we're fitting a tube against two or more other tubes, it can be quite difficult to understand where it needs to be notched. You might just want to eye this in or you can use a notch tracing tool to kind of get this into position but those notches will require a lot of different methods. You won't be able to use the paper template method for example, you won't be able to use a notching tool with a hole saw, you'll have to really just eye that in and work it out as you go. Sometimes there is no proper process for it but if you have a grinder with a nice radius wheel on it, then really anything's possible as long as you work out the lengths and then work this into position. So that basically covers most of our notching today, there are a whole bunch of tools that you can get for notching, you don't need them all.

If we have some form of finding an angle with an angle protractor, so something like our digital angle finder, we have a vernier so that we understand the diameter of our materials, of the wall thickness. We learn the paper templating method and then we practice our notches and perfect them with a file, then you're going to get pretty good fit ups and again that's important when we're looking for a nice weld. So that basically brings us to the end of the webinar and remember if you've got any further questions, please feel free to ask in the forum and I'll be happy to answer them there. Thanks for joining us and hopefully we can see you next time.