Making 3D Printer hot end heat sinks

January 16, 2016

I have been improving my hot end a little bit at a time and I was trying to print this cover for the power supply case I'm making for my nas, but I have been having a heck of a time getting that done. It basically has many rectangles and my current set up kept jamming with this part. The brass piece that holds the tip is the only one I haven't changed and it's the one that had or barely had any threads in it. So it's been basically clogging up in the same place which is inside of this piece. I tried fixing it, but in the end that just didn't work. The original threads were barely there. I tapped it but it was still loose. I should mention that I got one of the early printers. So today I finally took it apart and while I did that the top inner piece broke on me when I tried taking it out. I just decided to make me a new piece. I had a small piece of aluminum stock that was just the right size. So I went ahead and decided to try my hand at cutting the square on my mini lathe. I just needed to face the sides since it was just about the size I needed so this turned out pretty good after all. Here are the pictures...

The original piece that I desperately tried to save but just didn't want to be saved.

My faced aluminum stock. If I remember correctly this was 6061 aluminum. I got this a long time ago. I didn't have any brass so I just used aluminum.

So far the piece came out pretty square from what I could tell. 

I used the old part to get an idea of what size I should make the parts. I found that I could make two parts at the same time so that's what I decided to go with since it was easier to do this as one piece rather than two. Parting the pieces was my last step which was interesting to say the least, but I went pretty slow and it all worked out in the end.

So I got to working the old fashion way. I used a metal ruler, my 2 inch square and my scriber to mark the piece where I needed the holes to be. The last time I did any of this was back in college a long time ago, but it was fun.

I almost drilled one hole too big because I thought it was the larger one, but managed to fix it. I don't have any dykem I think it's called so my marks were a bit harder to see, but not impossible. I just had to scribe a bit deeper. I'll have to look into getting some of that.

These are the lines that will show up a bit but it was not big deal after I lightly hand sanded the parts down. I just needed to take out the sharp edges.

The two heat sinks finally done.

Here's a comparison with one that came with another hot end I had ordered. That small piece was not square at all. I decided to use a screw on the side to hold the heater like the original instead of that cut as the small one had. It's a much better design because it keeps both, top and bottom square.

And the final piece all ready to go. I'm currently printing a part I have been trying to print but couldn't because my hot end kept jamming on me with this particular part. It's now going great and I haven't heard a blip out of the motor.

January 19, 2016  update:
After putting this together I found that the hot end was jamming just after about a minute. I changed over from the stainless steel body to the aluminum to the original ptfe body and I still got the same thing. I even made two new tubes to use with the ptfe inserts and still it was not working. I even put the original all metal piece at the bottom and one with an insert at the top, yet this was still jamming on me. As you can see there are not that many parts to this and this was just really getting annoying not being able to print anything. I knew my new aluminum blocks where fine, but I did find out that aluminum expands much faster than brass as I found my tip to be way too lose right after it would heat up.

I took it all apart again and decided to take an even closer look at what the cause may be. I decided to manually push the filament through while I had the parts out and sure enough, the hole at the top wasn't quite clean and the filament was getting caught on it. So I cleaned that out to make sure I could push the filament with my hand without any resistance on both tubes. This solve my first problem. The next one was to figure out why the tip was getting so lose after I had tightened it down before putting together. Yes it was tight, but it didn't matter. This is how I also broke yet another tube. I also took a closer look at how the filament was being melted and it looked like it wasn't being melted at the tip where it should be melting. I decided to just screw the tip all the way in so that it would also touch the block as I had the small neck or non threaded part off the block. This gave me a nice solid tip. Sure enough as soon as I put everything back, the tip was heating perfectly and I did not get a single click on my new print which meant everything was heating up in the tip properly as I was getting some cold filament there. This took two days to figure out and now it seems to be working the way it's supposed to.

I should mention that I decided to go back to the original PTFE tube to keep the heat to a minimum, but I am using two pieces with the 4 mm inserts in them. This keeps the heat off the filament at the top and down at the bottom. This also worked with the stainless steel piece, but I found that ss doesn't dissipate heat too fast. The aluminum heat sink I found to also reach high temps very fast so the most effective way to keep off the heat at the body is to use the original ptfe or make your own ptfe body from a ptfe rod. This should get you going if you decided to use your own aliminum heat sink as well.

 Here I'm taking this hot end apart for the nth time.

 New screw I found and drilled.

Holes are cleared.

 Cutting the ptfe insert.

Testing with the original PTFE body as well. Still got the same jam as the other two.

 Here's where I noticed the filament was getting too hot up above earlier.

 Final set up again. You can now see the tip is screwed all the way into the block first. I then screwed the tube on the other side to make sure the filament gets heated in it correctly. This is critical or you will get cold filament that doesn't get melted even if everything else is working. Of course the filament also has to slide in correctly without any binding anywhere in the tubes. Get these correctly and it works like a charm. I forgot to mention that when I installed the threaded tubes with the ptfe inserts, I butted the two open sides in the middle against each other so that the metal surfaces would mate in the block and of course the other side is where the filament comes into the hot end. This seems to work.

 New print started. You can see the details of the lines much more clear now. So after all that trouble shooting, it's working correctly again with the new block. Now I can go back to concentrating on my designs again while I print some more prototypes.

I found this PTFE rod in amazon. I may get one so that I can turn my own hot end body if I need another. I'm sure you can probably find these almost anywhere now.

January 20 update:
I got another jam and was thinking oh what now after putting this together. The filament roll was done and I was getting ready to change the roll but I thought I let it go until it finished. That's when the clicking started but then I paused the print and realized that it was clicking not because it was jamming, but because the filament was bent in one of the holes holding it back. That was a moment for sure. As I was taking out the filament I still noticed a not so even melting even though it was working. This is when I decided to just go ahead and make an inner washer to put between both tubes as it was originally designed. I wanted to keep the heat below as much as possible now. So I took this apart and went ahead and did this even though I wasn't crazy about it. Needless to say it has still been working again.

The steps I took were the following:
1. Tighten the tip to the aluminum block as before.
2. Put the other tube into the block from the top.
3. Cut a washer from the original included 5 mm ptfe tube for the ptfe body. I don't have any 5 mm outer diameter but found that this is that size, so I just used that. The washer is only about 3 mm thick anyway so you are not taking a large chunk.
4. Screw in the original ptfe body to the bottom tube. This pushes the washer into place. Mine still works, but I may get some ptfe rod to make a couple more. This is just the route I may go with myself but you can just get a whole need hot end from craftunique. If the price goes down some more I may just go that route. I don't need anything else at the moment but I just thought I mention this.
5. Screw the top tube down the ptfe body. Don't tighten it yet.
6. I found that putting filament through the hole unit and then snugging it gave me the best result. If you tighten it without doing this, the filament will be too tight there and won't slide through easily. I had to back that off and then found that this was the best way to make sure there was no binding. Otherwise your filament will bind if you forget to do this after you put it back on the printer.
7. Install the hot end back on the printer and level the bed. Yes I have decided to go back to the almost original setup because it just works. I could use the metal pieces but they just add heat even with the inner ptfe tubes. Even thought I did get those to work, I think the guys had a good design from the start, they just needed a slightly thicker washer I think and a better block at the bottom or at least better threads to prevent the oozing.

 This is the end that started holding my filament back and when the clicking started. I usually just take the roll off towards the end, but I just didn't on this one. So it got me.

 Here's the piece of filament I took out. You can still see the uneven heating even though it was working. This is before I put the inner washer back. Now the heat should not travel to the top tube at all. Well at least not like before when it was butted to the lower one.

Here's the new washer in place. Yeah this is a bit annoying, but it's not too bad once you get it all figured out. Now the hot end is working just as when new. As long as the filament slides freely by hand before you put it back into the printer you should be fine.

May 4, 2016 Update:
After printing three of the new large nas parts, the printer extruder started acting up on me again. I keep getting jams. Basically the center ptfe piece is causing this problem once again.  Anyway, without getting into too many details, and trying to get this working in the middle of the night with just the parts you may have is always challenging, but as I started at this trying to figure out how to get this middle problem fixed or at least working better, here's what I came up with.

 First I thought I could just use a piece of this ptfe tubing I had to hold both inner metal pieces. Unfortunately it's a tad too big so the pieces slide in and out. Not good and it's not straight.

 Then I looked at the tubing I had and since it's the middle piece that turns out to be the problem I figured, why not take out the two inner ptfe tube pieces on each of the tubes and cut a long straight piece with some space in between to keep the spacing between the tubes in the middle. This takes care of two things at once, it gives me a nice straight shot to the bottom and also allows me to space the tubes so the heat doesn't travel to the upper tube. Remember, you are trying to keep all the heat at the tip end not above or the top.

 Measuring the tube.

 So, here's what I came up with and what this looks like. The tube is the same size as the inner tube that comes in those metal threaded pieces. This is a  4 mm OD with a 2 mm ID. I bought the tube a while back to cut pieces for the inner pieces. But instead of cutting two small individual pieces, I can just cut one longer piece. Having two separate middle pieces definitely seems to be a problem over time vs having one straight shot down for the filament.

 As you can see it is much smaller than this piece here, but it doesn't matter since the other tube will sit around it and one a small amount will be outside the piece in the middle where the space is.

So the middle ptfe beige piece needs to sit as close to the block as possible to prevent it from getting lose. If not, I found this to get lose over time. I then threaded the top by hand, and then snug the bottom a bit with the wrench, just so that it's not lose. Then the top with pliers. Just don't over do it since it's plastic, but just going by feel you know where to stop. Once I put this back, it seems to work fine again. For how long, I don't know, but I have now gotten rid of that middle piece that always keeps getting smashed and now I also have a nice straight shot down so I don't have to worry about the filament getting stuck in the middle. I just did a small print and it seems to work fine again. That middle piece seems to be a huge pain in the rear and I hope this will take care of it. I don't even have to worry about the two ends in the middle being perfectly straight. I just need to make sure the top has that nice concave to it so the filament slides without a problem and the bottom is nice and flat against the block. I don't know why I didn't think of this before, but this looks good without having to spend a bunch. I do prefer this setup so hopefully it will keep working for a while. Keep in mind that I did add a top and bottom ptfe ring on mine just to space that out a bit from the block. The top was to keep the heat away from the top when I had the metal holder but I just left it there.

May 10, 2016 Update:
After getting this put back together I kept having the same issue. The non-stop clicking. So I took it apart, put it back together and when I tried to put the filament through, I noticed that the Inland glow in the dark filament had imperfections where it actually ballooned and that's what kept it from feeding. So I got bit by the filament this time.
After fixing this problem, the clicking persisted, no matter how many times I leveled everything. I then noticed this. The filament was melting right in the middle.

 Here's where this problem happened. Right before it went into the feeding tube. So check your filament for these types of problems even if you have used this before. Apparently it can still happen.

 Then it happen farther down the line here.

  Here's the piece I cut off so I could start this large cover again.

 In the end, since I took this apart, I used the new block, hoping that would fix the problem with new tubes which was pretty much the same thing. I also use another nut for spacing and now have used one long tube but got rid of the spacing and have both tubes butted to maintain a constant temperature or prevent any air space in the middle. I also decided to use a new stainless steel tip to test one out because it also has a slightly bigger hole, but every now and then, it will still click and since I know it's a nice straight shot and the parts where they need to be, I decided to bump the temperature up to 220c. Yes this is high for PLA, but now the same filament seems to be happy. So even with the brass tip apparently I needed to bump the temperature up more in order for these parts to be happy. In short the parts seem fine, but my temp may have still been a bit low for this setup before. I just started a new print and aside from a few clicks due to my bent guides in a few areas, it's printing so I'll keep an eye on it, but this is where this is. It's been really frustrating, but at least this seems to be melting the filament now. I just started another large print so hopefully it won't give me any more fits.

I just ordered some of these types of nozzles since they are longer and similar to the original. I'll test once I get them if my current setup stops working. The two piece type now is a bit more uneven due to the tip having to be all the way in and that leaves a shorter area for the top tube. Which should still work fine as long as they're snug, but maybe this would help with the temperature balance. Hard to say since I also got some mixed results before too, but they do exist so why not.

I also got me a piece of .5" PTFE rod from ebay. I couldn't find any metric, so this will have to due so I can make a few more holders later on. I may just make the middle hole without any fins since I don't think it will matter much.I would prefer to use the metal pieces, but that seems to work against this. Maybe if I feel like testing a bit more I may try testing a bit more later on.

May 12, 2016 update:
I found out that the stainless steel tip worked, but I wasn't getting nice layers, so I have gone back to the smaller hole size tip. It's still .4 but for some reason the stainless were a bit larger. I also decided to use two new tubes with the ptfe insters but sure enough, due to the small concave end which I ended up using on the top and at the bottom butted next to the tip, that alone causes and air space which basically causes jamming. So in short, I ended up using the harder bolts I had made with the flat on one end and the open side facing the top butted next to the open side of the other tube in the middle. I also still used the single long ptfe tube for a straight shot, but also used the outer ptfe piece to hold both threaded tubes together. This seems to work the best. I also noticed that I ended up bending the lower tubes when removing them, so those long brass tips above should work fine since they are more solid and only have space for the filament to go through. If it's flat that would be better, if not I will most likely need to take that concave out since having any small air space causes any hot air in there to melt the filament, causing a jam before the filament hits the tip end. That should be easier than trying to make my own threaded inserts and would work much like the original with better threads. Mine just had the worst threads if any.

May 24, 2016 update:
I finally got my new tips above and I can tell you that I like them. They will need an 8 mm wrench instead of the 7 mm I bought for these. Not a big deal and I actually like the slightly larger nozzle. The hole is the same .4 mm and it seems to work just fine. I still got clicking on this until I decided to just manually turn the knobs until it started printing without any clicking. I then moved the hot end to the middle and measured the actual distance of what worked. I then went ahead and did the leveling again and measured the distance the bed was at. Low and behold the tip was touching the bed. In short it looks like even if I do the leveling, the actual distance will change once I start a print. I found that the distance was about .45 mm vs .30 mm. I'm now using some metal feeler gauges and now just use the .45 mm gauge to level the bed. Once I start printing, the tip is already adjusted correctly. This is something that I still can't figure out why it does this, but it still hasn't been fixed, so this is the way I have now fixed this. It's not an actual fix, but it works. Now here are a few pictures of the actual parts.

They seem to be well made just make sure not to go cavemen on them when you tighten them. They do have to be snugged though as I was getting some leaking even on these. I'm still testing this to make sure it's not leaking again.

I had a chance to use one and take it apart again. It was nice and stuck, but since these are more solid, it came off fine with the wrench and no bending as I was also careful not to pull to one side to hard.

May 25, 2016
Today I finally decided to just get the new PTFE parts made. I got four and two were not good since the plastic is pretty soft I only made very small fins, just so that they are not so slippery and to keep them strong. I was able to machine a few of these from the bar stock above. I also managed to get a tighter thread in them which seems to be holding well.

This is the one I just put in the cb and did a very small test, but canceled since the part was making the cb make a weird thump. It was sliced with and old version and also was a file I downloaded from thingiverse I think so not a good test file. I also did learn to work with plastic on the mini lathe since this is the first plastic piece I have actually made. Overall I am happy with the result. The .5 inch bar works just fine and I didn't even bother truing the outside. As long as the threads are straight and the ends, it works just fine. I'm just happy I have some spares now so I can concentrate on actual printing, hopefully. I did get bit on one of these other Chinese tubes as I swapped the first one with a nut on it and installed the new one, I found that the hole was not big enough for the filament to even fit it. Not cool after you have put everything back together. Live and learn.

I forgot to mention that I used a 3/16 drill bit to make the hole since I can't for the life of me remember where I put the metric drill bit I got. I then used the 5 mm tap, but that didn't leave much thread. I was trying to work my way up to see how tight the thread would be, but then I switched to the 6 mm tap and it worked great. I can do this since it's plastic and it just left a nice tight thread which is what I wanted to make sure the tubes where held together better. My old one seems a bit more brittle after using it for a while.

I should also note that you can now buy all sorts of heater blocks so you don't need to make your own if you don't have a mini mill. I have yet to see any brass blocks.

I am now finally doing a smaller test print with this new pieces to make sure it works and there are no leaks or any other issues. There's only so much you can change on this and I think I gone through many of them.

July 4, 2016
I finally got to using this setup and then this happened. The tips seems to be unfinished causing quite a blockage. After I got the drill out and drilled the step off, they started printing again. Unfortunately the filament inland batch I got this time, also seems to be pretty bad adding to the problems.

I decided to change the hot end with another since it was still acting up a bit and that went much better. So just don't go too deep with the drill and stop as soon as the step is taken out. You will feel it with the hand drill.

I was happy with the setup until I tried to print a large part after doing a few small parts, then this happened.

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