Discussion in 'Project Logs' started by Andreas | Brodholm, 19 Aug 2016.
Very nice, looking forwards to seeing more.
I'm squeezing in another update before new years. I have had a fever the last few days but I am all better now. I am also going away for a few days but after I get back its time to assemble the outer case!!! Cant wait!
Time to get to work with some drilling and tapping! I will try to explain this as thorough as possible since I know some of you are not that experienced with drilling and tapping and are looking to make your own cases. If you already know the exact procedure you can skip the small "tutorials" I have written in these walls of text
Okay, some tips when drilling. Make lines on the correct places. And use a die to mark the location. Use a smaller size diameter if you are drilling a large hole. For these holes (3.3mm) it is okay to go with the correct diameter at once. When you are drilling, be sure to have higher speeds for small diameter drills and lower for higher diameter drills. You want to get a nice cutting speed on the flutes.
The reason why you should pre drill with smaller diameter drills is that the cutting speed is much less on a smaller diameter drill and you want that to achieve a certain cutting speed, lets say X mm/min then you need to go Y amounts of RPM. But if you have a big drill you still do not want the flutes to go over X mm/min so you have to lower the RPM to not have the outer part of the flutes go over X mm/min. This means that the closer to the center you get on the big drill you get slower and slower cutting speeds. In the center you are basically just pushing the tip through the material instead of cutting. Giving you a bad finish and usually off centered holes. So that be sure to think about that when drilling.
Basic formula for drilling should be: Mark the lines, do a die mark, drill a hole with a smaller diameter at faster RPM, switch to the correct size diameter and slow down the drill. And when you are drilling aluminium you really need some kind of cutting fluid to insure that you don't rub the aluminium and therefore breaking the drill. So use cutting fluid to make sure those chips don't weld to the drill. Also, do peck drilling, breaking the long chips. And if you are drilling deep blind holes, take the time to remove remove the drill from the hole all the way up and remove the chips if the hole is deep (I would say 3-4 times the diameter).
Following these steps will take longer than just "drilling holes". But it WILL save you parts and time in the end. The quality of the holes and precision will be better, and having to deal with broken drills is a huge pain in the ass. Remember, broken bits can seldom be drilled out due to them being as hard as the drill itself, remember you can only drill materials if you are using a harder material than the one you are drilling.
There are a lot of techniques to get drills out of holes if you mess up, and I am not going to go in much deeper than this. But if you do break one, I would recommend searching on Youtube and you will find lots of videos showing how you can try to get them out. Sometimes you just have to scrap the part.
Anyway, this is how the results should look if you follow all the steps.
I drilled these with a piece of aluminium clamped do the the very thin wall I had to bore here. Did not want the material to "bend out". Probably would have been fine anyway but the extra time vs to having to redo the part was a easy calculation.
There are several types of taps for different kind of holes. The one to the left is a blind hole version that you can use when you have shallow holes that you need to tap all the way down (almost all the way). The right one is for normal through holes. You can see that its much easier to get in and align since its tapered. The left one here is a bit better for aluminium I have found. I ordered that specifically for aluminium and blind holes. Both of these are M4 taps from dormer. And each tap is about 30 USD or so. You can get cheaper ones but you really want good taps with good material. Ebay taps looks basically the same, but they are not nearly as good and break much more often. You want the material hard and flexible at the same time, something that is not very easy to achieve.
Before taping be sure to countersinc the holes so the thread goes in easily and you get no burrs after you have threaded the holes. It also looks much nicer and you will have a easier to to get the screws to thread.
Use some kind of lubrication, I am using a thin oil that works good for threading.
Be sure that you go down straight into the holes, enter a millimeter and then check from all sides that you are going perpendicular to the surface you drilled. The thread is like a drill, it will actually drill the whole off center if you have a bad angle and snap or stop when you go to out of center.
Go slow, make sure you are in center, after you have turned a few rotations, turn the other direction half a turn or so to break the chip, and then continue threading. Take your time. If you think breaking a drill is bad, breaking a tap is worse. It is also much easier to break a tap since they are thinner and harder usually.
Be sure you are in center and only put axial force into the threading and no radial. If you use to much radial force you WILL break these small threads.
Here you can see some finished holes. Notice how the countersink will help your screw to go into the threads instead of "sliding along" the surface as you try to find the hole.
Since doing one hole is pretty much the same as doing a 100 I am not going to show all of the holes. Next up is assembly of the outer case
I've done a fair amount of "just drilling holes" and like everyone (probably) I think I know what I'm doing. Interesting and useful to read someone else's tips. Breaking the chips when tapping is something I was already doing. When drilling alu I thought nice long curly 'hair' (mainly from a conical step drill) was a good thing and wasn't breaking it...am I wrong?
I've been using WD40's cutting lube for both drilling and tapping. Seems to help but the spray can can be somewhat enthusiastic!
Got any tips for how to make sure the tap is perpendicular? It can be difficult to judge by eye when you're right up close.
Same with drilling, I was thinking about a drill press but was hoping (wrongly?) if I did get a CNC I could use it to do this too.
Hope you're feeling better. I've just come down with the cough my son had :-C
When drilling alu I thought nice long curly 'hair' (mainly from a conical step drill) was a good thing and wasn't breaking it...am I wrong?
I actually don't know, I have been applying the same techniques as I do with steel. I might be wrong but It seem to work for me. If anyone have more info on this please do tell!
I never took a photo of it but I made a special tool for tapping straight. Just took a cylinder and drilled a hole that the tap could just fit through. And I can put that against the surface and you always get good holes. But usually I just enter the hole with the tap and look from 2 angles and I am set.
A CNC router is not something that replaces a drill press. Since the drill press is mostly have Z travel with very little X and Y. A drill press is a very useful tool. But a normal hand drill is usually enough.
Finally enough part to assemble the outer case! All outer cover panels is held by magnets and will be glued after anodizing.
Just a blast to assemble it! Finally you go from just flat pieces to an actual case. It was a lot of threading before I could do all this but I was very careful to get everything right.
This is where the button assembly will fit.
Very pleased if I may say so. A very proud moment and a huge relief to have the outer shell together. Next up is the inner segments of the case!
When it comes to tapping, may I also recommend a tapping block to ensure that the tap enters the hole fully perpendicularly?
Here's one I knocked up from a nit of scrap brass:
Nexxo: Nice, thanks. Looks like I'll be making some tools as a first project then! :-D
Andreas: Thanks for that. The logical progression (in my head) was "I need a drill press to keep the drill perpendicular when step drilling larger holes....might as well be a mill if I'm going to invest....might as well be CNC if I'm getting a mill!" so it's good to know where the logic is flawed rather than make expensive assumptions!
Good to see the chassis coming together. Looks great so far. What are the marks on the front panel? I know it's not a problem as they'll just polish out; just curious what made them. Marks from clamping or scuffs on the original stock?
LED light strip along the gantry looks like a new addition. Nice.
I love this new generation of crazily over-built rigs that the general public would think were a factory case.
"mistakes"= Tiny nick made by the bit that could be buffed out. You only get to use that word when you cut a pattern out on the wrong side of a panel.
The marks was made by me, tried out the new scotch brite grind/polish discs on some of the area. Worked out really well.
Those also happen
It's brilliant to see the case coming together. I'm just blown away by the level of quality here - Cheapskate mentioned factory cases but this looks superior in quality to pretty much every factory case I've seen. Stunning.
Thanks mate, glad you like it!
Also can anyone recommend a glue for neoprene rubber on anodized aluminium? I tried "contact glue" but that only works "ok" and you can easily tear of the piece from the aluminium.a
It similar but needs higher RPM and your cutter needs to generate chips,not long swarf.
WD40 is a good Alu cutting lube,no problems there
Finally back home, have started the huge job of editing pictures. About 4000 pictures more to go through, hours of video etc... Anyhow, next update is done! More to come!
First inner part done!
What could this be?
Pro tip to myself, when you refill the cutting fluid, put the lid back on...
You are starting to figure out what this is now I bet
Close to done!
You guessed it! The back for the motherboard tray!
Time to get serious. Doing the motherboard tray. Over 3 hours of machining calculated on this piece + setup and tool changes. This is 20mm of aluminium. When the pieces start to get this big they do not only get expensive but also a lot of work going in to them!
Time to flip this badboy around.
Main body is done! Time to do the channels for the cables
Jump forward in time a few weeks. Decided on cable paths. Milling these here. But I thought that I would post these together since it is the same part
All done, and VERY pleased with the results. Took quite a bit of work to figure out how I wanted this and to get the design balanced visually.
You are doing EVERYTHING with the CNC cutter? How small pieces are possible to make? Is it also possible to do everything with acrylic too?
Looks really good, seems like you spent some time doing the cad work...
Well, you can basically do as small as you can hold down and you need to have small end mills also.
Doing most of the things on the CNC. Still A LOT of stuff with manual drills, drill press, tapping threads, filing square inner corners, glass blasting etc. I can basically keep busy and do things when the CNC does its thing. But I usually do not have time to do all the manual work before a piece is done.
And then there is usually at least an hour in just programming the piece in CAM, on the big piece for example I believe it took over 5h to program. And then hundreds of ours of regular CAD for the whole case of course
Dat slab of 20mm aluminium...
I just squealed like a little girl.
Man, That would have taken me 3 months.
It was time to bring out the big guns
Well, It was machining for 3 hours on both sides. Then add the cable channels (another 2h), then all the setup and fixing. I would say this was a 12h + part.
Well, if you don't have a CNC you just gotta work on those steady hands
EDIT: Also, is this just me or have all the pictures been un-resized?
It looks great, with the small issue of the sides being off center.
EDIT: EDIT, ohh shieeeeee, the page got even bigger!!! I am guessing this has something to do with the site being down earlier
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