Author Topic: Top Hat Speaker Build (Read 15200 times)

ibuildstuff4u · « **on:** October 08, 2013, 11:47:21 PM »

My 16 year old nephew drew up some prints for some desk top speakers and asked me to make some parts for them. The speakers are full range and the "Top Hat" will disperse the sound in a 360* area. The body of the speakers is made out of PVC plumbing pipe and the rest is aluminum and wood. The pipe will be painted when done and the aluminum parts will be polished to a shine.

My challenge this week is to make the "Top Hat" part. It starts off with a 5" diameter piece of aluminum that I rough cut in to two 3.5" pieces. Then it's off to the lathe to face off the pieces and turn them down to 4.750 in diameter and 3.250 in length. I had to use my 4 jaw 6" chuck as my 3 jaw was too small so it took a while to dial in each piece to the lathe.

Dale P.

ibuildstuff4u · « **Reply #1 on:** October 08, 2013, 11:49:18 PM »

After turning the parts I moved over to the mill and set up the rotary table. (This is one tool I don't use enough in the shop!) I set up the rotary table to drill three holes equally spaced apart in the two parts which will be used to mount them to a face plate. These holes also match up with three of the six holes in the speakers and will be used to hold up the top hat in the future.

It was a pain to get the parts dialed in to the rotary table, but after they were dialed in I drilled the three holes and tapped them for a 10-32 bolt which will hold them to the lathe face plate.

Dale P.

ibuildstuff4u · « **Reply #2 on:** October 08, 2013, 11:54:35 PM »

My CNC lathe doesn't have a face plate so I bought a 6" chuck adapter for the lathe and also mounted it to the rotary table and drilled the same three holes so I could bolt the parts to it in the future.

So here is where I call it a night. I have both parts ready to turn on the lathe and the face plate is ready to mount to the lathe.
Now here is the problem!!! I'm having trouble programing the CNC lathe! I don't have any background with CAD so I have to relay on the Mach 3 wizards along with writing G codes. I can set up the lathe to cut the taper and radius, but they don't blend together very nicely when I perform test cuts. Hopefully I can have it all sorted out soon as I want to cut these blanks and see how they look!

Dale P.

ibuildstuff4u · « **Reply #3 on:** October 09, 2013, 12:04:16 AM »

For anyone that can help with the G code, I'm ok with changing the Top Hat part a little from what is pictured. I just as long as the taper is around 2.5" long and is around 2.75 inches in diameter in the end. One nice smooth transition would be fine as the shape can be a little different than what is shown in the picture. Just let me know if you have any questions.

Thanks for the help!
Dale P.

AdeV · « **Reply #4 on:** October 09, 2013, 08:14:39 AM »

Nice work sir! Interesting speaker design too... I might be tempted to try one of those myself...

Anyway, I'm wondering if the blend problems you're having are actually in the drawing rather than the lathe; it looks to me like the radius cut is too deep, so the "exit" of the radius isn't at a tangent to the tapered section. When it cuts, is it leaving a sharp corner on what looks like a bit of a bump?

As you'd included a dimensioned drawing, I took the liberty of copying it but using the tangent arc feature, which suggests a radius of 1.239" instead of 0.881" - does that help?

Brass_Machine · « **Reply #5 on:** October 09, 2013, 08:52:59 AM »

Dale,

Nice work so far... I wish I could help with the G code bit, but I am still relatively new at it.

That is an interesting speaker design. Your nephew is lucky to have an uncle who is willing and able to make things for him.

ibuildstuff4u · « **Reply #6 on:** October 09, 2013, 06:27:42 PM »

AdeV Thanks, I really like the revision and that is the look we are trying for. I think a large part of my problem is that I don't have my tool programed into Mach so it doesn't know what type of cutting profile Im using on the tip of the tool. This works Ok when I just use one wizard, but when I try to run two wizards back to back they don't blend well at the transition. I should stop and take the time to fully set up Mach but I'm not fully sure if I understand how it all works so it's just easier to not mess with it!

I'm going to make a test piece at half the size and see what I can come up with. I will post pictures in a day or two if I get some free time to work on it again.

I just have to make sure to not mess up the real part as the metal is expensive! My nephew was able to get the large pieces of aluminum for free from school, but if I have to buy more it would be $40 per top hat, $80 for the pair. I figure it will be around $100 to $120 for all the aluminum to build both speakers if we didn't get the large pieces for free. I have priced it out because if these turn out nice I plan to make a set for my self!

Dale P.

Brass_Machine · « **Reply #7 on:** October 09, 2013, 06:44:17 PM »

Hi Dale,

Take your time with the cut... If the transition doesn't look too bad on the test piece, perhaps you could blend it manually? Files/sand paper and such.

Eric

Brass_Machine · « **Reply #8 on:** October 09, 2013, 06:45:49 PM »

Whats the gap for at the bottom of the tube? The spot that is between the two wood discs?

Eric

AdeV · « **Reply #9 on:** October 09, 2013, 07:02:07 PM »

Quote from: Brass_Machine on October 09, 2013, 06:45:49 PM

Whats the gap for at the bottom of the tube? The spot that is between the two wood discs?

Presumably to let the air move around behind the speaker cone. If you look at the back of one of your Hifi/surround sound speakers, you'll most likely see a similar vent, it means the back of the speaker isn't pressurising/de-pressurising the box all the time, which leads to better clarity. I think the reason it passes through a tall narrow tube is to try to stop the sound from coming out "backwards", not sure if that'd tend to cancel out the sound from the top, or just generally interfere with it.

ibuildstuff4u · « **Reply #10 on:** October 09, 2013, 10:46:37 PM »

The gap is so a bass port can vent from the top pipe. There are more drawings of the speakers that show the port, but I only posted a few pages of the print.

We are not sure if this is a good idea or not and plan to do some testing to see if it helps. I'm kinda hoping it sounds better with out the port because it would be easier to build.

I originally planed to make these parts on my manual lathe which would have been tough to make two identical ones, but thankfully I got my CNC lathe running and figured out a way to mount the parts on it.

Dale P.

Brass_Machine · « **Reply #11 on:** October 09, 2013, 11:42:13 PM »

Dale,

Wasn't sure without a clearer picture. Back in the 80s I dabbled in building speakers. Had a guy who built them as side business for clubs and such teach me a bit. Honestly, I don't remember a whole lot. I do have a book somewhere around here: Loudspeaker Design Cookbook. I have a much older version... has some equations on calculating volume etc of the box. Interesting stuff. You might want to suggest for him to pick up a copy, the older versions are a bit cheaper.

I have been planning a small speaker setup (in my head) for the new place (along with a tube amp). One of these days I will get towards building them.

Eric

Brass_Machine · « **Reply #12 on:** October 09, 2013, 11:51:29 PM »

Found some on-line calculators. Not sure how accurate they are:

DIY Audio and Home Theater Shack.

They have an interesting Tutorial as well.

It only gets crazier.

ibuildstuff4u · « **Reply #13 on:** October 10, 2013, 12:10:27 AM »

Yeah, I got him that book for Christmas last year! It's amazing how much science goes into building a speaker.
Im hoping to build some more speakers in my future too, but just don't have the time right now. I also have PCB boards for two different amps to build, but don't have the time or money to work on them. Hopefully I can have one of them up and running by next year. A tube amp would be really cool, but they seem to be expensive to build and I don't know anything about tubes.

Dale P.

Brass_Machine · « **Reply #14 on:** October 10, 2013, 12:33:29 AM »

I have some info on an inexpensive tube amp somewhere. I will find it for you... When I say inexpensive, I mean the tube cost. Somebody designed a decent amp around a cheaper tube. Just have to find the info. I have a couple of the tubes (6EM7), you can get em pretty cheap on ebay.

I ended up building a small practice amp for my brother in-law along with an effects pedal and got hooked.

Great book for a gift for your nephew.

NeoTech · « **Reply #15 on:** October 10, 2013, 04:08:51 AM »

http://www.the-planet.org/6EM7.html << this your speaking about maybe? =)

ibuildstuff4u · « **Reply #16 on:** October 27, 2013, 01:15:14 AM »

First of all I really like the tube amp link. That's something I will have to build some day down the road.

Tonight I was able to get in to the work shop and play around with the lathe. After a few tries I was able to get a part made at 50% of the size that the finished part will be. There is just a fine line where the taper and radius meet, but that should easily go away with a bit of polish.

I was just about to run the full size part when I ran into another snag. The part will not fit in the chuck so I bought a chuck back plate to use as a face plate and simply bolted the part to it. The trouble came when I tried to mount the face plate to the lathe and found that the face plate is 1/8" too short to fit. The nose of the lathe sticks out of the face plate! Now it looks like I will have to make up an adapter to hold the part out from the face plate so the nose of the lathe has room to stick out.

I'm really bummed as this was an expensive back plate make by South Bend and I was planning to re use it when this project was done to mount a new chuck for the lathe. Now it looks like it will be a $75.00 piece of scrap metal.

Here are some pictures.

Dale P.

mattinker · « **Reply #17 on:** October 27, 2013, 01:40:07 AM »

Dale,

Don't give up on the back plate, you may well be able to recess your new chuck to fit! On a chuck, the area around the base where the spindle is rarely critical. Back plates are ideally cast Iron to prevent locking on the nose thread. If you make a steel spacer for a new chuck, a thin plate would suffice, pinned to the back plate.

I'm tempted by by your speakers!

Regards, Matthew

ibuildstuff4u · « **Reply #18 on:** October 27, 2013, 01:48:35 AM »

Thanks Matthew for the advice about mounting a future chuck. Your probably right about making a recess on the new chuck, it's just something that I shouldn't have to do with a new chuck and back plate. I send Grizzly a picture and asked them to add some dimensions to the web site so people could see what they were buying.

Right now my main issue is mounting the Top Hat parts and the adapter that I will have to make so they can be mounted to the back plate. I really want to cut the full size parts out and see what they look like.

Dale P.

mattinker · « **Reply #19 on:** October 27, 2013, 02:35:57 AM »

Dale,

I understand what your saying about "I shouldn't have to do it on a new chuck" but I feel that machining is about making things work! Machining a backplate is just about making it fit.

Regards,Matthew

Brass_Machine · « **Reply #20 on:** October 27, 2013, 10:56:42 AM »

The 1/2 sized part looks pretty good. I bet you are anxious to cut the full size part.

Can you get a refund from Grizzly? Or you can just post it for sale.

Perhaps you could machine up a spacer ring? Mount that on the nose and then the adapter?

Quote from: NeoTech on October 10, 2013, 04:08:51 AM

http://www.the-planet.org/6EM7.html << this your speaking about maybe? =)

Yup. That is at least one of them.

Eric

ibuildstuff4u · « **Reply #21 on:** October 27, 2013, 08:03:49 PM »

I don't mind machining a back plate when mounting a new chuck, but I really shouldn't have to cut into a brand new Bison Chuck just to make it fit. I already drilled holes into this back plate so I can't return it so I will just make up a spacer and keep it for a face plate for future projects. I will see if I can find a deeper back plate to fit the new chuck when this project is done as I really want to keep the chuck stock at this time.

I spent a few hours in the shop and made up a spacer for the back plate. I only had aluminum on hand but it should work just fine. Hopefully I will be able to machine one of the full sized parts tomorrow night!

Here are some more pictures.

Dale P.

ibuildstuff4u · « **Reply #22 on:** October 27, 2013, 08:14:34 PM »

Eric, I used your idea about putting the spacer between the nose of the lathe and back plate. I originally was going to place the spacer between the face plate and part, but your idea was a lot better.

Thanks!
Dale P.

Brass_Machine · « **Reply #23 on:** October 27, 2013, 09:28:19 PM »

Awesome job Dale!

Eric

ibuildstuff4u · « **Reply #24 on:** October 27, 2013, 10:06:19 PM »

As you can see I had to switch around my chuck from regular jaws to reverse jaws a few times to make this part due to the small 4" chuck that I have which is why I'm changing both of my lathes to a 5" chuck. Hopefully that will keep me from having to change out the jaws as much in the future. I'm putting a Bison brand chuck on the CNC lathe, but just a china brand on the 9X20 as I hope to replace this lathe some day with something a little nicer.

Any one buy chucks from CDCO? Do you think they are the same ones offered by companies such as Grizzly and Little Machine Shop.com? I'm guessing they all come from the same factory in china.

Dale P.

ibuildstuff4u · « **Reply #25 on:** November 06, 2013, 12:28:52 AM »

Ok I finally had time to run the full sized part and it took a LONG time to run! It took over two hours to run and I ended up with a full garbage can of chips and a really warm spindle motor. Half way through I opened up the side cover to the lathe and ran a fan on the spindle motor to try to keep it cool as it was getting pretty hot. I'm happy with the finished part and just need to run it on the buffer a little more for a perfect mirror finish. The bummer is I still have one more part to turn!

Before I ran the part on the CNC lathe I decided to re chuck it up on my manual lathe and cut a radius on the top just to dress it up a little. I ended up grinding a custom cutter out of high speed steel to make the radius. The problem is the only way I can only hold these parts is with my 4 jaw chuck so I had to dial in both parts with an indicator before I could turn them.

Here are some more pictures.

Hopefully this weekend I can turn the second part and then make the other parts for the speakers.

Dale P.

Brass_Machine · « **Reply #26 on:** November 06, 2013, 12:36:18 AM »

Looks nice!

Eric

ibuildstuff4u · « **Reply #27 on:** November 23, 2013, 08:00:50 PM »

Ok, one side done. Just need to make one more!

Dale P

Brass_Machine · « **Reply #28 on:** November 24, 2013, 09:22:15 PM »

Looking good Dale. I definitely like the style...

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Author Topic: Top Hat Speaker Build (Read 15200 times)