Rev2 of the DIY Prerss
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Rev2 of the DIY Prerss
Hi,
Thought I'd update you on my progress. I finished my second rev of the press. Still needs some work, but getting better results. Here is a view of the current setup. I now have top and bottom heated platens with much thicker 3/8" aluminum plates for more thermal mass. Still using the cheap hotplate heaters, so there are still hot spots. I now have thermocouples mounted on each platen to monitor temperature.
I now am able to press two sided using a book like arrangement with top and bottom stampers mounted to thin aluminum plates. You can see the home brew bushes I machined along with 4 screws around the OD to act as hold downs. The book is loaded with the powdered plastic. I'm still using craft store 9mm polysterene beads crushed in a coffee grinder. The top is placed on the book and the assebly is inserted into the press.
The raw result is shown here:
I'm having some problems getting the pressed result to fill properly. In the center, there are some voids. Not sure if this is due to outgassing or improper pressure/temp profile. Right now, I have no way to measure platen pressure (I'm working on adding as gauge for this).
I have a crude trimmer shown here:
The finished record here:
You can see the voids in the center cutout area. I am also seeing small voids on both record surfaces (the top is much worse and currently unplayable. The bottom is palyable, but each void makes a loud pop on playback. Otherwise, the surface sounds pretty quiet. I can post a sample is any interest.
I have also found that cooling by dunking in a cold water bath does not work well. The water gets into the mould area and boils out the plastic and leaves gaping voids. The result shown here was done by letting the mold cool slowly. I need to build a cooling unit to speed up the process.
I need to do some tweaking, but I feel like I'm in the ballpark.
Mark
Thought I'd update you on my progress. I finished my second rev of the press. Still needs some work, but getting better results. Here is a view of the current setup. I now have top and bottom heated platens with much thicker 3/8" aluminum plates for more thermal mass. Still using the cheap hotplate heaters, so there are still hot spots. I now have thermocouples mounted on each platen to monitor temperature.
I now am able to press two sided using a book like arrangement with top and bottom stampers mounted to thin aluminum plates. You can see the home brew bushes I machined along with 4 screws around the OD to act as hold downs. The book is loaded with the powdered plastic. I'm still using craft store 9mm polysterene beads crushed in a coffee grinder. The top is placed on the book and the assebly is inserted into the press.
The raw result is shown here:
I'm having some problems getting the pressed result to fill properly. In the center, there are some voids. Not sure if this is due to outgassing or improper pressure/temp profile. Right now, I have no way to measure platen pressure (I'm working on adding as gauge for this).
I have a crude trimmer shown here:
The finished record here:
You can see the voids in the center cutout area. I am also seeing small voids on both record surfaces (the top is much worse and currently unplayable. The bottom is palyable, but each void makes a loud pop on playback. Otherwise, the surface sounds pretty quiet. I can post a sample is any interest.
I have also found that cooling by dunking in a cold water bath does not work well. The water gets into the mould area and boils out the plastic and leaves gaping voids. The result shown here was done by letting the mold cool slowly. I need to build a cooling unit to speed up the process.
I need to do some tweaking, but I feel like I'm in the ballpark.
Mark
Last edited by markrob on Tue May 03, 2011 8:49 am, edited 1 time in total.
- subkontrabob
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incredible project! Ghetto engineering par excellence!!
A little suggestion to the poster:
if you edit your post so that the picture links are tagged as Images and not as URLs like you did, the pictures would be directly embedded in your post.
The way it is now makes it a bit cumbersome to look at all the pictures, because it requires to open a new tab etc. If you don't know how to do it I can send you a step- by step instruction per PM
cheers,
Bob
A little suggestion to the poster:
if you edit your post so that the picture links are tagged as Images and not as URLs like you did, the pictures would be directly embedded in your post.
The way it is now makes it a bit cumbersome to look at all the pictures, because it requires to open a new tab etc. If you don't know how to do it I can send you a step- by step instruction per PM
cheers,
Bob
Ooooh ok , more clear now , the "book" details cleared my doubts with how can make the plates (I guess) , I was talking with moss for get some test stampers , but lot of projects now and I had it a little left and can't no continue with that until get the frame (now we only have the piston) , but sure I'll get it soon.
Best Regards and thanks for your dedication Mark.
PD : to mossboss , we talk again when I am with this issue again, sorry for the inconvenience , I was poorly organized and spoke too soon , sorry.
Best Regards and thanks for your dedication Mark.
PD : to mossboss , we talk again when I am with this issue again, sorry for the inconvenience , I was poorly organized and spoke too soon , sorry.
Very Busy days , some cutting works at least , soon online again
We must promote the use and abuse of vinyl records.
We must promote the use and abuse of vinyl records.
Hi,
Bob,
Thanks for the suggestion. I edited the post to add the img tags. I never took the time to figure out how that worked. You're right, it does make it easier to follow.
Tommie,
The puck method is the traditional way pressing is done. However, this requires very large forces as you have to squeeze the plastic material out to the edges of the mould. The adavantage of the Cook Microfusion method is that the material is already where it needs to be, so you just have to heat it to the glass transition point and allow it to fuse. Since the the material is in powedered form, its required less pressure to do this.
Mark
Bob,
Thanks for the suggestion. I edited the post to add the img tags. I never took the time to figure out how that worked. You're right, it does make it easier to follow.
Tommie,
The puck method is the traditional way pressing is done. However, this requires very large forces as you have to squeeze the plastic material out to the edges of the mould. The adavantage of the Cook Microfusion method is that the material is already where it needs to be, so you just have to heat it to the glass transition point and allow it to fuse. Since the the material is in powedered form, its required less pressure to do this.
Mark
- monkey1553
- Posts: 42
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Hi,monkey1553 wrote:Mark,
It looks like things are really coming along. Good job! As far as the non fill goes. Have you thought about adding more of the ground vinyl to see if that helps? Maybe its just not loaded with enough of the vinyl granules? Just a thought. The new plates look pretty slick!
~Michael
I've only done a few runs so far (its a pain processing the kiddie beads in the coffee grinder), but I have tried larger amounts of material (I've run as low as 30 grams to as high as 60 grams) with no real change in the results. I just placed an order for some powdered PVC from an ebay vendor to try as a test. This is much finer ground (the consistancy of flour), so it will be interesting to see if that improves things. I am also in the process of outfitting the bottle jack with a pressure gauge so I can control and repeat the pressure. I need to have a means to reproduce the pressing conditions once I find a set of parameters that work.
Here is a scope photo of the issue:
Mark
looks to me like either the PVC is not flowing as well as it should while heated, or some sort of moisture is being released.. What the hell do i know, lol..
I can help you with microcontroller programming once your ready for that, there are all kinds of sensors for pressure and heat measurements.. Automation of the jack is most likely possible..
I can help you with microcontroller programming once your ready for that, there are all kinds of sensors for pressure and heat measurements.. Automation of the jack is most likely possible..
generally its for reproduction.. but i like to play wif it sometimes..
Re: Rev2 of the DIY Prerss
Hey Mark,
Any new progress on this? It looks great, did you ever get the powdered pvc and try using that?
Any new progress on this? It looks great, did you ever get the powdered pvc and try using that?
Re: Rev2 of the DIY Prerss
Hi,
This project has been on the back burner for me, but I do still intend to get back to it at some point. I did get some fine powdered PVC used for pyro applications. On a quick test, it did not perform well, but that may have been due to lack of proper heat and dwell time.
Mark
This project has been on the back burner for me, but I do still intend to get back to it at some point. I did get some fine powdered PVC used for pyro applications. On a quick test, it did not perform well, but that may have been due to lack of proper heat and dwell time.
Mark
Re: Rev2 of the DIY Prerss
mark,
have you tried PLA (polylactic acid) as a material?
have you tried PLA (polylactic acid) as a material?
generally its for reproduction.. but i like to play wif it sometimes..
- Steve E.
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Re: Rev2 of the DIY Prerss
Does your plastic have any trace metal in it? I think that's typically an additive for the sake of bubble removal, but I don't know the details.