Hacking The Teenage Engineering PO-80

[markrob]

Hi,

I've attached stl's for two new parts I created. The pulley is a dual LPI design so you can switch between about 85 and 100 LPI by moving the round belt between the two diameters on the pulley. This should be printed with a resin printer for best results. The second part is a simple anti-backlash washer that goes in place of the 10mm white washer on the underside of the case that holds the rack in place. This can be printed FDM. There are two holes to be tapped for 2-56 screws (or metric equivalents) that are used to adjust the tension to keep the rack from wobbling around by adding some friction. I glued two small 1mm thick felt pads to the bottom of the part. The screws apply some pressure to the pads. You can set the rack pretty tight as long as its not too hard to move by hand. There is plenty of torque available from the main motor to overcome the friction due to the large reduction ratio of the gear train. See the attached photo.

Mark

[pennstate913]

Did my first cut with the 7" mod and while it plays and there is sound/music..I'm having some issues with tracking (could lower volume to solve) and also the beginning of the recording sounds distorted due to the cutter heads weight affecting the 5" tables stability..any thoughts on how I could solve that? Also not sure if its my stylus being worn out, but I can't seem to get clear audio anymore and Im not sure why, ideas? Much appreciated as always.

[markrob]

Hi,

I think that its marginal due to the construction of the bearings used and the fact that things are not so stiff. I printed a 6.5" platter to provide a better base for the blank, but you still run up against the deflection of the platter at the outer radius of the 7". If you drop the down weight, you don't emboss as deep and then you have tracking issues. I've been thinking of adding something to stiffen up the bearing mounts to see if that could help. The question is if its worth the effort. I have also been considering developing a low cost base that could use most of the mechanical parts from the PO-80 but improve the performance. I've probably spent way too much time on this, but its been fun to push the envelope.

Mark

[pennstate913]

Do you have the stl for the larger platter? Yeah I was only using about 20-22g of weight so I probably need to increase it a bit..35-40g is what others have recommended, but i'm worried it'll be too much for the stock motor, so Ill have to upgrade it too. I was thinking of trying to do the same..not only a larger base, but I wanted to replicate the gearbox as well.

[markrob]

Hi,

I upgraded my motor to a small stepper. It now has plenty of torque and the speed is stable. The larger platter stl is attached. I had to do some machining to get it to run true. I made a special sanding disc that made that easy, but you would need a metal lathe to fabricate it. You may get lucky and it will work fine right out of the printer. I'm working on a stiffener for the base. I should know by tomorrow if it works. I'll post back here if I get somewhere.

Mark

[pennstate913]

Found this and it might be insightful: https://digitalcommons.calpoly.edu/cgi/viewcontent.cgi?article=1344&context=imesp

[pennstate913]

Just noticed the stl file. Thanks again Mark, you are a true gentleman sir.

[farmersplow]

Guys, you are totally crazy! And I'm fascinated by what you're doing! I'm curious to see where it ends. Probably never

[mrd]

The one on the left is the head I made using the same sized driver from the Gakken. Both actually currently have Gakken styli fitted too. Have tested that they "function" but only crude 'tattoo' style cutting since I don't have the mounting arm or carriers made yet.

This looks cool and could be useful for a couple of other projects too - are you hapy to share the stls?

[markrob]

Hi Everyone,

I've been working on a new cutting arm and head design and I thought I'd share it here.

New Cutting Arm Low Res.jpg

This is a complete replacement for the existing arm with several new features.
1. Allows for a head tilt angle adjustment for cutting or embossing.
2. Adds ability to adjust the length of the arm so that the stylus is on the centerline of the platter after adjusting for the stylus angle.
3. A new head holder that gets rid of the spring clip and stylus of the original PO-80/Gakken and replaces it with a stylus holder that works with a standard Presto short shank stylus.
4. In place of the spring clip, a pivot point style bearing that is fabricated by grinding points at the end of two machine screws (or you could use pointed setscrews off the shelf). Type 4-40 or metric equivalent.
5. Improved frame and retaining ring for the Dayton driver. There is now a lip that allows you to make sure the driver sits at the correct position when glued into place.
6. Easy assembly and repair if the driver is fried.

I've attached the STL files with folders for resin printed and FDM parts. I experimented with printing machine screw threads into the STL for resin parts. This worked out very well on my printer, but you will still need to run a tap to clean up the holes. I modeled 4-40 and 2-56 threads but I can provide metric versions or raw holes if needed. You will also need to fabricate a shaft for the arm as I designed all of these parts to print with minimal supports. The shaft is 6mm OD with a 1.5mm ID and is 37mm long. I machined it out of aluminum in two parts to be able to drill a 1.5mm hole 37mm deep. I'm sure you could 3D print or find another means to make this. The connecting rod from the dirver to the stylus holder is 1/16" x 33mm (sorry about the mixed units). I used HSS drill rod and cut to length with a Dremel

This is still under testing, but I'm getting some good results. Especially embossing at half speed 45 RPM. I can also provide the Fust0on 360 files if you want to mod.

Mark

[mrd]

Hi Everyone,

I've been working on a new cutting arm and head design and I thought I'd share it here.
New Cutting Arm Low Res.jpg

This is a complete replacement for the existing arm with several new features.
1. Allows for a head tilt angle adjustment for cutting or embossing.
2. Adds ability to adjust the length of the arm so that the stylus is on the centerline of the platter after adjusting for the stylus angle.
3. A new head holder that gets rid of the spring clip and stylus of the original PO-80/Gakken and replaces it with a stylus holder that works with a standard Presto short shank stylus.
4. In place of the spring clip, a pivot point style bearing that is fabricated by grinding points at the end of two machine screws (or you could use pointed setscrews off the shelf). Type 4-40 or metric equivalent.
5. Improved frame and retaining ring for the Dayton driver. There is now a lip that allows you to make sure the driver sits at the correct position when glued into place.
6. Easy assembly and repair if the driver is fried.

I've attached the STL files with folders for resin printed and FDM parts. I experimented with printing machine screw threads into the STL for resin parts. This worked out very well on my printer, but you will still need to run a tap to clean up the holes. I modeled 4-40 and 2-56 threads but I can provide metric versions or raw holes if needed. You will also need to fabricate a shaft for the arm as I designed all of these parts to print with minimal supports. The shaft is 6mm OD with a 1.5mm ID and is 37mm long. I machined it out of aluminum in two parts to be able to drill a 1.5mm hole 37mm deep. I'm sure you could 3D print or find another means to make this. The connecting rod from the dirver to the stylus holder is 1/16" x 33mm (sorry about the mixed units). I used HSS drill rod and cut to length with a Dremel

This is still under testing, but I'm getting some good results. Especially embossing at half speed 45 RPM. I can also provide the Fust0on 360 files if you want to mod.

Mark

This looks awesome Mark, thanks for sharing!

[concreteutopia]

Amazing! do you have a recommendation for an online 3d printer that we can order prints of your stl files from?

[markrob]

Hi,

Glad you find this stuff useful. I do all my printing here. The price for a FDM machine is so low these days, that it would pay for itself pretty quickly. Even the resin printers are low in cost. They are just a mess to deal with due to the chemicals. The potential issue sending them out is how they decide to orient the part and the need for any supports. When you print your own parts, you can experiment to get the best results. I'm sure there are great online printing services available. Maybe some members will have good recommendations.

Also, If needed, I can supply my Fusion 360 files if you want to tweak them.

Mark

[Togirdor]

Everything looks amazing, i've been doing my own improvements to the original normal-priced gakken ez recorder (with no extra paint jobs). When i find some time i can share them.

I came to notice that now it's impossible to find brand new replacement needles. Did someone bought the whole remaining stock to resell them? What are you people using as an alternative?

R

[markrob]

Hi,

I am embossing here. You can flip the Gakken/Teenage stylus 180 degrees and it works fine as an embosser. You get much longer life in this mode. I decided to make the new version of the head and arm so that you can use a standard Pesto short shank stylus instead of the Gakken/Teenage stylus. There are more sources for this style, NOS, used, and new. Mike Dixon sells a nice cone style embosser in this format. If you find old dull cutting styli, you can turn them and use them for embossing as well as long as the tip is not broken. Long shank styli can be easily cut to short shank length.

Mark

[apoklis]

WOW this is incredable stuff. You have really took this to the next level. How long until the varible pitch version come out ? LOL Too cool ! At this point you can just print the whole thing.

[mrd]

WOW this is incredable stuff. You have really took this to the next level. How long until the varible pitch version come out ? LOL Too cool ! At this point you can just print the whole thing.

It is seriously impressive work!

Cross-post to the gakken mod topic... I added a separate pitch mod ha ha

https://www.instagram.com/p/CP3KXQqHsNv

[markrob]

That looks really nice!

[CutR]

Hi Everyone,

I've been working on a new cutting arm and head design and I thought I'd share it here.

Superb work Mark they look great, I look forward to getting these printed up and seeing how they perform. On a side note I have returned back to cutting and I'm getting some decent results
using the clear protector disc you get at the top in a pack of bulk CDs. I'm not sure what the material is I assume its PETG but when using TESCO brand multi surface spray applied to disc and some heat from a heat lamp and the stylus weight set-up so its light as possible but still producing swaft. I'm able to get a near noise free payback without the constant shhh from the stylus scraping away at the disc. There is some noise from what I assume is the swaft building up around the stylus. I would like to do some testing with a heated stylus, can someone tell or post a link to the terminals that you attach the nichrome wire to?

[kugelblitz]

Hi Markrob
I've put togheter your parts; really cool work!
I was wondering if you could elaborate on the homemade amp you use to drive your head? I might like to copy it.
Curious to try it out now!

DSC00598.JPG