(Yet ANOTHER) DR250 Build Thread!

[escapemcp]

Update:
Sorry for lack of posts recently, I have been very busy - although not due to speaker building
A few days ago I managed to get the router template sorted for the top hat:



I'll have to add in some reinforcement on the back side to give the screws enough material to bite into:


On Saturday I managed to get both the cabs up to the same point. They are now waiting for the drivers:


On the second cab, I had to attach the horn assembly to the top about a quarter of an inch away from the line it is supposed to attach to. This was to make both cabs look the same from the outside. The error was due to the horn support on cab 2 being at a slightly different angle to cab 1. I must have checked that 3 degree angle about 10 times, but I guess I should have checked it 20 times!! Because the array is thin (front to back), when you put the top & bottom on it magnifies any small errors that are made. I have added in a sliver of wood to the half rounds in the middle of the butt cheeks to compensate, so the 1/4" flexible ply shouldn't cause me any problems. Is it worth also compensating for this when it comes to attaching the PVC pipes?? If I do compensate, it just means that there is an extra 1/4" in the path length (at the top - it decreases down to zero at the base) - I would think that the difference in this case would be neglible. If I don't compensate for this, then the whole butt cheek 'turn' will be slightly wider than spec. Do you think I should try to correct this with more thin bits of wood before the PVC gets attached, or is 1/4" on the turn (well, at the top at least) not going to affect things that much?

Today I have spent quite a while building a new tweeter cutting jig (as I am unable to proceed on the cabs themselves). I decided that it would be better to build a new jig, rather than reusing my old jig that cut the tweeters a bit too much (which necessitated adding an extra couple of tweeters in my Otops. I had a bit of melamine worktop in the garage, so I used that for a nice flat base to build the jig on. It was handy also, as my saw blade for cutting plastic is actually too small for the saw - it cannot cut all the way down to the 'base' of the saw. Here is the jig for the first cut (and an ominous looking blade - more on that later!):


For the second cut I am going to use a strip of wood like this:


I cut a couple of tweeters with the 'reduction' strip screwed in (you can see the screw holes), before I discovered that it was cutting them a tiny bit too much (so the tweeters were thinner than they should have been (by about 1/32"). I could continue to use this, but I am really trying to be bang-on accurate on this build.

Gratitutious shot of most of the tweeters (and I have even more in a box!!):


And finally, whilst I was trying to cut a new strip for my tweeter cutting jig, this happened:


I had heard you guys talk about kickbacks (and seen injuries from them from Harley & Bman), but I had never had one myself. That has now changed and I now understand how much they musy hurt. Luckily the chop saw rotates away from me during the cut, so it picked up this bit of ply and rammed it against the body of the mitre saw. It happened so fast, I didn't even see it move. One moment the ply was sitting comfortably being cut... the next it was all mixed up with the guard. I had respect for the saw before, but that has just made me have a whole lot more respect for it... and for Bman & Harley who were on the receiving end of one of these kickbacks... ouch!

I decided to call it a night at that point! More tomorrow (hopefully).

[Tom Smit]

I decided to call it a night at that point! More tomorrow (hopefully).

Good decision as it will probably allow you the time to process the whole event, and come up with potential solutions.

[escapemcp]

This evening's progress:
Pretty boring for you lot tonight. I managed to get all of my 2nd cuts done on 40-odd tweeters. The end result looking like this:



I did slightly cock up by forgetting the top and bottom tweeters, so had to cut a few extra after I had done all the double cuts
I think that I still have enough tweeters for 2 straight arrays I may well make those (or at least cut them) whilst I have everything set up.

I then moved on to the 45° cut. After flipping around my tweeter cutting jig 180°, I proceeded to make a 45° cut so that I could see where the saw was going to cut. I used my digital callipers to place a wooden block however many inches away from the cut line that it is supposed to be - I spent quite a while getting this bang on, as I will be using this as the only reference for the 45° cut. I reckon it is within a few thousands of an inch of where it should be :thumbs up:.
I puzzled over how to make this cut safely, and came to conclusion that gaffer tape - whilst a PITA to keep taking up and putting it back down - was the way I would tackle it. I figured that this was less of a PITA than going through the rest of life with one (or more) less digits :double thumbs up:



I forgot to take a photo of a test 45° cut, but just look at your instructions for a pic... mine look identical to that (for once!)

And that's your lot tonight.

Hopefully I will get some more posted tomorrow night, although I have other stuff to do tomorrow, so progress will probably be less than tonight (and the progress that is made will just be of some more tweeter cuts!)

Quick question: I have been getting some 'chipping' on the tweeter 45° cut (on the side closest to the camera in the above pics). Does any one have any suggestions how to avoid this? (I'm sure you guys have!) I have been 'chopping' straight down on the cuts, although I may well try sliding the saw through the cut to see if that improves things.

[ncgrove]

Throw on an abrasive blade or at least one with more teeth.

[Bill Fitzmaurice]

Throw on an abrasive blade or at least one with more teeth.

+1. Abrasive blades minimize the possibility of kickback.

[escapemcp]

Bugger

I'll just have to be careful on the cuts.

[Grant Bunter]

Bugger

I'll just have to be careful on the cuts.

I have a 60 tooth blade on my compound mitre saw, even then, I had a little chipping here and there, mostly when I tried to cut to quickly. Go slow.

And I found when you put the melded arrays together, all the chip outs will fill in nicely.
I take it you don't have ABS?
Keep all that nice plastic kerf "dust" to use in acetone (or whatever you're going to use to dissolve it), to make your goop to glue everything together.
It's not like the array needs to be sealed nowadays, as the module itself seals the driver chamber, not the array.

[escapemcp]

Go slow.

BINGO! No problems taking it very slow. I was worried about the melting that results when you go slow, but it was easy just to pick off. Cut the rest of the tweeters and zero chipping that I noticed



And all 40 ready to go:



I have been so much more accurate with these tweeters than the ones in my Otop array. I would think that joining them all up should be easy as they are all the same size

I take it you don't have ABS?
Keep all that nice plastic kerf "dust" to use in acetone (or whatever you're going to use to dissolve it), to make your goop to glue everything together.

I tried that method at the school where I work... stupidly I tried to use zip ties instead of ABS

I also managed to get some 100mm PVC pipe yesterday, so tried to cut that using this jig:



The pipe goes in here (where my measuring circle is):



Despite all of my jiggy goodness, the pipe just wants to close on the cut (as Bill mentions). In the end, I just used my jig to provide me with a nice straight line to mark along, and then I just use a hacksaw. Far easier than trying to cut it with a table/mitre/circular saw and as a bonus, you get the edges roughed up for free.

One thing I did notice is that my 100mm ID pipe is about 104mm OD, but the gap it has to span is larger than this. I assume the pipes get stretched a little to make a nice round turn?

So the pipe is sitting right against the edge of the bit of ply, but on this side I get a gap:



Anyway, after messing around with the pipe, I managed to get something that looks a bit like what I have seen on here:



I will probably recut some of these, as one of the pipes suffered quite badly when it closed in on the circular saw. Now that I know how to do the cut accurately, I might as well utilize that knowledge and recut the pipes (sorry, I mean reflectors ) to a closer tolerance.

Still awaiting the driver. 8 days after auction close and no sign of it The guy I am buying it from has 1500-odd feedback and 100%. I think I need to threaten that and I might get some action his end. At least this downtime is allowing me to sort out some of the shittier jobs (like tweeter array manufacture). When it does turn up, I should have a working cab in only a few hours

[escapemcp]

FINALLY have a 3010 in my possession - man, they are heavy (when compared to the 2512s I have in my Otops).

This evening I managed to cut the woofer spacer and sort out the mounting, but I never had much time as I was watching England crash out of the World Cup.

I'll make a nice long post (with many pictures) for you all tomorrow.

[escapemcp]

Managed to fire off a few pics before coming into work today. On this build I have used 13mm M6 hex drive threaded insert thingy-ma-bobs which I driven in from the 'wrong' side. I don't own a drill press to ensure that these are perfectly straight, so I opted for another method to ensure that these were in straight enough so that I could mount the driver. I firstly clamped the driver into position, and then put an M6 bolt all the way through to the other side. I then attached the hex drive nut all the way to the start of the hex key hole. Then I could just insert the allen key and drive the thing home... the bolt going through the driver and the nut ensured that everything was lined up. The end result looked like this:


I need to route a tiny bit out of the driver spacer, so that the 13mm nut isn't pushing up the spacer (as it is now). This is an easy job. Might also need some longer bolts (35mm ones shown here)
4 nuts down and I was able to mount the driver I love sinking my nuts as deep as they will go



Haven't slap tested as yet, although it does look like there may be a bit of work to do with the sander. I did make it a slight bit oversize just in case.

EDIT: For nut 'joke'

[escapemcp]

Sickky, sickky, sickky!

It's a long weekend! Looking forward to some serious progress over the next 2 1/2 days. Although I'm ill, I'll probably just potter today and see how it goes. It'll take my mind off this sodding cold if nothing else

[biggerrigger]

Don't rush anything. Take your time and do a good job and you will be done before you know it.
When it comes to firing them up for the first time make sure you take the time to measure the output and EQ to your liking before you dump the power to them.
It will make all of the hard work worth it in about 3 seconds flat.

[escapemcp]

Yesterday's progress:

It was a bit of a PITA yesterday. Not only was I ill, but I also hit a fair few snags... but hey, if these were easy, they wouldn't be a '9' on Bill's scale!!

Started off by mounting the spacers:


Ok, that was easy. Then onto making the front supports. I made this jig for cutting the 20 degree long cut:


Only used it once, once I realized that I should be making that cut first and not at the end after the cuts to allow for the sloping of the top & bottom Still, it did a good job on the one cut it did have to make.

Then I moved onto the front supports. cutting the supports was easy(ish), but it was making room for the 3010 driver to fit in that caused all the problems. I was under the impression that getting the 3010 into the cab would be easy due to the truncated square frame, but this was total BS. It is the magnet that causes the problems, and the 3010 has a bloody big one (=more problems getting it to fit). I originally planned to get the driver through the gap by sliding it at about a 70degree angle until it hit the baffle, and then dropping the other side down. To do this I had to put the driver right in at the top of the cab, in order that I could drop the driver in as deep as it would go (the middle of the cab having the throat filler in the way and the bottom has the top hat). I tried a test cut in a test support... this didn't work, so I then moved onto the next plan. This one did work (although I forgot that I no-longer needed to avoid the throat filler, hence this cutout also being at the top of the cab!):



Step 1: Driver frame into triangles:


Step 2: Ease other side of driver into the chamber:

Ooh, that's tight:



Then once through, the driver has to be moved into position and bolted down.

I did almost cock this up after installing the cleats (as the driver needs to be butted up against the top of the cab when installing). A quick mod later:


So the end product looks a bit like this:


I'm planning to add a reinforcing strut to the front supports (like the one Bill mentions in the plans, but his is only temporary), which will sit just below the centreline of the driver (to allow the back of the driver to vent. I understand that this isn't a requirement, but the fact that Bill has one in the plans for use when installing the sheaths, suggests that there is a bit of weakness here. For a small bit of ply, it's a nice insurance.

So onto today. I'm still having issues with the PVC pipe. Now the width of the "letterbox" to which the pipes attach is way over 4". I understand that the pipe to be used is 4" ID. I could only get 100mm ID pipe, but that's pretty well much the same as 4" (1.6mm (1/16"th) difference). Even with this difference I am easily a quarter of an inch too short. Looking at sketchup, the suggestion is that this is due to the pipe walls of my pipe being too thin. On my pipe they are 2mm at most (5/64"), but sketchup suggests that your bits are 1/4". Are your bits of pipe really this thick, or was this simply done to make the transfer to sketchup easier?

Thanks,

Aidan

[escapemcp]

Oh... and my PVC glue is brewing

[escapemcp]

Has no-one spotted the deliberate mistake??