Cutting ally shapes

[Chris152]

My son's making a replacement instrument panel/ fairing bracket for his bike, replacing the steel with aluminium. He cut the shape below which is ok for the job in hand, using a hacksaw, a rod saw blade (I think it's called - a round-profile abrasive cable on a mini hacksaw frame) and a file.

If he wants to make more of these and with a better finish, what would his (home workshop) tool options be? I guess cnc on the mill (£££), but what other options for getting a smooth, efficient cut?

Thanks for any thoughts, Chris

 

[Barking Mat]

I'd farm it out to a laser cutting company, not really expensive.

 

[Kram]

Whats the thickness?
A nibbler makes quick removal of sheet. Holesaws or slugger drill bits are great for larger concave radius curves.
A good fine cut file would smooth off those convex radius curves nicely, if its marked out well, easy to follow lines.


Another is to have a tem0late 3D printed, I believe @Dr.Al used one with a router to cut out some shapes with good effect. Edit: not router, it was plasma cut. Good tools though I have not yet got a great finish quality on my cuts, they are very fast.

Heat Treatment Oven

The last couple of posts have discussed this rather complicated control cabinet circuit: This time, I'm going to talk about a much simpler (and much cheaper to build) version of the circuit: It's worth noting that there are definitely cheaper and simpler ways of making it than this. I...

www.mig-welding.co.uk

I recently aquired an aluminium cut carbide burr and they make extremely quick work of shapes and metal removal, with a great finish. Requires a die grinder. A burr probably wont work well for sheet much thinner than 3mm. They require a steady hand an understanding of climb/conventional cutting.

This 6mm thick bracket was all cut with a burr (drills for the holes ofcourse), used files only on the straight edges.

More photos here

Stuff you have made today

Firepit is warm. I have been tidying my logs. Had this old angle frame, tied fence mesh to it. Its a bit small could have done with being longer or taller.

www.mig-welding.co.uk

Stuff you have made today

10 of these , got one finished now for the rest316 Stainless !

www.mig-welding.co.uk

Now however you cut the shape, the front face can get marked. Its best to leave the protection film on, or apply some film. Once done, burnish or sand it uniformly. A dip in causic then anodise would look very good and give future protection.

 

[DAPPH]

A thick HDF or chipboard kitchen door for a jig and use a router to cut them just make sure the alu cannot move nor the jig move so use pins in waste area to locate precisely then clamp up
Any decent mains powered router with a half inch bit should do two at a time with ease . It will take a while to carefully set things up but once it's done you can be like a production line , do as many operations as you can before bending
Make the feed in close to where the bend will be and finger file it square .

I've often routed up to half inch thick alu either from a walk in , a careful plunge cut or along a very strait edge
IIRC route so the cutting edge moves along the direction of rotation it gives a cleaner cut Check with " Fizzy " we did his alu trailer together a few months ago .

3 mm is a breeze so long as everything is pin located & securely clamped , hang the cable over your shoulder to keep it out the way .
Work at the most comfortable height you can .

 

[keithski122]

Jigsaw and a file.

 

[addjunkie]

Band saw is ok for sheet ali up to breeze block sized chunks

 

[Chris152]

Thanks all, good few suggestions for us to think about.

The sheet he's been on today is about 1.5mm. I don't mind investing some money in this, he plans to make a living from welding/ forming in the longer run. Would something along these lines be good for this and future projects (this is just something that came up since DAPPH's post, no idea if it's good)?

https://www.amazon.co.uk/Genmitsu-3030-PROVer-Accuracy-Precision-Engraving/dp/B0CH9KCQ6C?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&smid=A19H5JAATTXASW&gQT=1&th=1

(Preferably used! £££ :-( ) We've been learning on the lathe and mill manually and I know at some point he needs to get into cnc - would this be a good start?

 

[Kram]

What does he intend to make, sheet metal fabrications or solid machined parts?

The one you linked appears expensive for its limited capabilities.
If you have space for a CNC router then the ready to use parts to build one have never been cheaper. Several forum members have made them recently.

 

[Chris152]

What does he intend to make, sheet metal fabrications or solid machined parts?

The one you linked appears expensive for its limited capabilities.
If you have space for a CNC router then the ready to use parts to build one have never been cheaper. Several forum members have made them recently.

He's learning to work on old cars and bikes, so a combination of sheet and solid machined. OK, we'll have a hunt for the router builds - thanks.

 

[Misterg]

Would something along these lines be good for this and future projects

I would say no, particularly with the spindle shown. Might be of use with an upgraded spindle - it's not the power that matters, it's the stiffness. It will never be a 'production machine'

If you want to get an idea of how it will perform on aluminium, it's pretty much the same as the one shown in this video (aloominum from about 13:30 if it doesn't go straight there):

He shows the recommended feed rates for the 1/8" end mill at 10,000 RPM as 150mm / minute (6") feed rate and 0.075mm depth per pass (0.003"), with a machining time of 4-6 hours for a ~80mm square part.

Even at the very conservative feed rates, it still chatters enough to put your teeth on edge. He doesn't help himself, as it looks like a chewy grade of aluminium (1100??) and no lubrication, however, from my experience with a similar spindle, I'd say that is as good as it will get without a stiffer spindle.

If you discount the aluminium machining, it would be a real machine to get into CNC, however so would a similar looking ~£300 machine.

I built my own, but it cost about 50% more than the one in your link, despite endless shopping around and waiting for parts from China.

If interested:

Desktop CNC 'Thing' build (includes welding!)

I’d never particularly wanted, or seen the need for a CNC machine, but the cheap, ubiquitous table top routers (“3018”, etc.) that have appeared on Amazon, Ebay and Youtube over the last few years sparked my interest – can you really get a working CNC machine for £150 ?? And so it begins…...

www.mig-welding.co.uk

 

[julianf]

Thanks all, good few suggestions for us to think about.

The sheet he's been on today is about 1.5mm. I don't mind investing some money in this, he plans to make a living from welding/ forming in the longer run. Would something along these lines be good for this and future projects (this is just something that came up since DAPPH's post, no idea if it's good)?

https://www.amazon.co.uk/Genmitsu-3030-PROVer-Accuracy-Precision-Engraving/dp/B0CH9KCQ6C?source=ps-sl-shoppingads-lpcontext&ref_=fplfs&smid=A19H5JAATTXASW&gQT=1&th=1

(Preferably used! £££ :-( ) We've been learning on the lathe and mill manually and I know at some point he needs to get into cnc - would this be a good start?

How competent is he? (or are you, i guess)

Whatever machine you buy, off the shelf, will, sooner or later, break.

If you build it yourself, when it brakes, you will know how to fix it.

I built the machine that cut the part in my avatar almost 20 years ago, way before you could buy that kind of stuff off amazon.
Its been through multiple iterations of control boards. Stacks of dead or repaired spindles. Rewires, and reworks, but the frame and the linear components were quality (THK and the like - high end Japanese, rather than low end Chinese) and that is where the accuracy comes from. Or rather repeatability, i guess.


I cant really get a feel for the size of the steppers on the amazon thing, but theyre not big. The steppers (and the linear stuff) are the expensive bits. Big steppers and you can increase the mass of the moving parts, but still have reasonable acceleration and deceleration curves. Small steppers, and, to drive a machine with any speed, the mass / inertia has to be reduced etc. etc.


Have a look on ebay for second hand linear stuff. The z-axis on mine was previously living in a clean room enviroment, doing precise, rather than heavy work, and will always be superior to the kind of stuff on the amazon link. Sure, its cost, new, would exceed the whole amazon machine (just for the linear part of the z) but its not like they cant be found used, if you look about.


A friend got one of the "cheap" cnc machines (about £500, i think) - mod after mod to try and get it right, and its not like he uses it now.

 

[Chris152]

Thanks both.

@Misterg - I'm exhausted just looking at that build. Amazing work. If you've seen Homer Simpson's spice rack, you'll get some idea of how it'd look if I tried to copy your build.

@julianf - looking at Misterg's build, I'd say we're not competent enough yet. Or at least, if we did attempt a build, it'd totally displace any other work for a long time to come. But now we have some direction and know a bit better what to watch for, I'll start searching ebay etc to see what's out there.

 

[julianf]

Occasionally I outsource to laser.

I do this when there's a whole load of parts with minimal holes (a mechanical mill is "relatively" good at cutting internal holes and "relatively" poor / slow at cutting external outlines, whilst laser costs seem low for the external outlines and relatively higher for the holes)

Or...

When I know the alloy is troublesome. I used to do a repeat job on a specifically finished sheet that was a 1000 series alloy. Someone with more skill could probably cut it fine with a rotary cutter but, for me, it was never worth the time and effort (and expense) of figuring it out when I could outsource it to laser.


What I mean is, as suggested earlier in the thread, don't be "afraid" of outsourcing. I have a machine thats significantly more capable than the Amazon one and STILL outsource as, sometimes, it's just easier to do so.

 

[Chris152]

Occasionally I outsource to laser.

I do this when there's a whole load of parts with minimal holes (a mechanical mill is "relatively" good at cutting internal holes and "relatively" poor / slow at cutting external outlines, whilst laser costs seem low for the external outlines and relatively higher for the holes)

Or...

When I know the alloy is troublesome. I used to do a repeat job on a specifically finished sheet that was a 1000 series alloy. Someone with more skill could probably cut it fine with a rotary cutter but, for me, it was never worth the time and effort (and expense) of figuring it out when I could outsource it to laser.


What I mean is, as suggested earlier in the thread, don't be "afraid" of outsourcing. I have a machine thats significantly more capable than the Amazon one and STILL outsource as, sometimes, it's just easier to do so.

For the moment, it's about learning as much as getting the parts made - so all the suggestions above are helpful but it does seem time to dip our toes into cnc in one form or another.

It's also worth saying that while he wants to do more of the sort of component in the first post, he's not really looking to make multiples of the same thing - rather, it's about being able to cut one-off components for different bikes that he's working on. Maybe a few to sell on if others like what he's doing. I'm guessing outsourcing is only really cost effective if you're getting multiples done, or is that wrong? Cheers.

 

[Chris152]

ps - Might it be easier/ cheaper to convert the mill to cnc? It's a Sieg SX3, so apparently suitable for the conversion but would it be as good as a router for this kind of job?

I watched this just now but still not clear:

Differences Between CNC Routers vs. CNC Mills | Fictiv

Everything you need to know about CNC mills vs. CNC routers, when to use a CNC mill or CNC router, and our best tips for success. Learn more.

www.fictiv.com

 

[julianf]

I'm guessing outsourcing is only really cost effective if you're getting multiples done, or is that wrong? Cheers.

It depends...

If i want a 1-off steel part cut at my local laser place, i will give them a thickness range thats acceptable to me, and ask them to put it on whatever theyre cutting at the time. That way they can throw it on whatever job has some spare space.
If i need it a specific thickness, the price or the lead time will increase.

For alloy work, i either supply the material, in which case i fill the whole sheet, or i use their material, in which case, again, i fill the whole sheet. Doesnt matter so much what the parts are, as a load of different parts are just someone opening cad files. What matters more is filling the sheet. Noone wants to load a sheet of specific material for one part, and then unload it again. So what gets cut is neither here nor there, but you want to make a situation where someone can load up a sheet, hit "go" and come back when its all cut. So the whole sheet (less the web) gets sold, irrespective of what came out of it.

Or you just accept that you have to wait to fit on the side of someone elses paying job. But, certainly at my local firm, this is a possibility with ferrous, but not so much with alloy.

1-offs, quick, in specific specs, are always going to be money.

 

[BrokenBiker]

I'd be doing that with a jigsaw, and then either some good quality files for final fettling or gentle use of a drill mounted flap wheel, carbide burr and sanding drums.

 

[Ian X]

I cut 6mm alu plate to make several tank cradles for a friends boat. If he isn't going into production a jig saw will more than suffice, accurate to a millimetre if the hand skills are up to it. Finish with half round and flat files. I cannot recall the smallest radius I have cut in alu with a jigsaw, fairly small, certainly enough to fit tacho and speed clocks for a friends Guzzi T3, neatly too. If its thin stock I glue it to 5 or 6mm ply with PVA and soak it off later, stops that raggedy edge when there aren't enough teeth within the cut.

 

[Chris152]

I've never had much success with jig saws, they seem to have a mind of their own. How about a scroll saw, could that work? They seem more controllable on tight curves.

 

[graffian]

I've never had much success with jig saws, they seem to have a mind of their own. How about a scroll saw, could that work? They seem more controllable on tight curves.

Cut straight across curves you don't think you can follow.
Do sort of tangential cuts to the cutting line, so you can remove as much of the big bits of scrap as you can.
Then make multiple small cuts[radially] in any scrap left and finally trim the little 'fingers' away.
File the ziggy zaggy edge until your happy.

My bandsaw has made the jigsaw redundant, as long as the piece of ali fits in the bandsaw otherwise it jigsaw time.