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Project Logs / Re: 3d printer - Leapfrog creatr conversion
« Last post by BillTodd on Today at 06:28:47 AM »
Yes, I did look at 3point mounts, but decided that corner mounts were simpler to implement . Hopefully, itll be just the one PITA adjustment session.
Project Logs / Re: 3d printer - Leapfrog creatr conversion
« Last post by WeldingRod on January 23, 2022, 08:49:45 PM »
3 point mounts are your friend on this stuff...  much easier to adjust.

Sent from my SM-G715A using Tapatalk

CNC / Re: Printer Enclosure.
« Last post by shipto on January 23, 2022, 12:15:17 PM »
I have made a bit of progress despite my kids seeming to think that dad can do without that free time nonsense  :lol:
I printed new mounts for the X/Y steppers and mounted them and have slight redesigned the belt ends/adjusters, still need to drill and tap the adjusters for some M3 bolts but I might wait until my friend comes back for that his Hobbymat is much better suited for such small stuff than my Harrison is.
Project Logs / Re: 3d printer - Leapfrog creatr conversion
« Last post by BillTodd on January 23, 2022, 07:50:08 AM »
I was not happy with the glass bed , I could not get things to stick to it and it took an age to heat to even 50'C, its 240w heat way too small for such a large piece of glass.

While watching the Prusa XL launch , I was taken by the idea of a segmented bed , so decided to build one for the FrogSpawn. While sourcing a suitable piece of cast tooling plate from the 'works' my friend overheard what I wanted it for and promptly donated ten 120x100 heater pads  - :-) perfect.

The mod involves bending the front of the existing Z plate , to remove a nice little 'finger-shear'  between the plate and the front of the frame. and mounting it below the ball-screw nuts to increase Z range. Four rectangular bars fixed to the underside of the Z-plate and a rear support , stiffen the Z-plate and provide mounting points for the Kastal 300 bed-plates

The heated bed-plates will mount on springs at each corner , with screws for adjustment.  Once properly adjusted the bed should stay trammed and level.

The nine 240vac 120w heaters will be controlled from a RaspberryPi Pico with a 9 way PID written in microPython  . 

The problem I have yet to solve is how to control the bed temperature from Marlin or, via g-code, from the BTT display controller.

Ideally, Marlin would be able to talk to the Pico via a spare serial port and report temperatures back to the display. However, I found no way to do this in Marlin :-(

My work around plan , is to intercept or monitor the serial data between the BTT LCD and the BTT Octopus board and intercept the appropriate M-codes .

Interception , means breaking the like between the two boards and inserting the Pico , but now the Pico would have to handle all the traffic and could be a potential bottleneck. 

Monitoring means just sniffing the data going to the Octopus board and picking up the bed control M-codes as they pass by. In order to let Marlin know the bed temperature , the centre plate's thermistor would have to be paralleled with both the Pico and the Octopus  . Any thoughts?
Our Shop / Re: My week this week, my workshop videos!
« Last post by hermetic on January 22, 2022, 01:51:47 PM »
Fordson E1A major, Rebuild.Part33  In which I get all the small parts painted ready to reassemble the pedals and footboards, a short week but good progress, if you have lots of small and medium sized parts to paint, best hang the lot up and do them all at once with a spraygun, makes a better job, covers all the awkward shapes and then LEAVE THEM TO DRY! you know you'll make a mess if they are not hardened off!!
Phil, its bloody cold in East Yorkshire!
Metal Stuff / Re: New lining for the iron furnace
« Last post by vtsteam on January 21, 2022, 01:11:16 PM »
One of the facts I like about casting is that there are a huge number of variables...and so, a seemingly infinite number of  problems and approaches. And so, it tends toward creating a personal style for the person casting. What I like about it is, it's still an art. And an art based on personal experience.
Tools / Re: Rear parting toolpost
« Last post by PekkaNF on January 21, 2022, 03:16:47 AM »
Yeah, started thinking how much support I need to resist bending and turning. Actually pretty much on cantilever beam. Why not to put support under the tip, a little doodling on the paper, then 1:1 scale drawing on paper and see how to clear the rotating part in most of the use cases. Last step was the height control. I realized that I don't need stop on QC tool holder in the usual manner, because there must be adjustment on the jack screw: Threaded the holder body and put there nut and standard hex socket screw.

Then I needed to figure how to hold the insert blade securely in the holder. The blade had rounded edges, one dove tail curret had just the perfect rounding (and bevel) to mach. Hold down is simple, Just a cross bar and set screw top of it to press it down. I considered a key or pin to draw it inside, but all fits were hard push fits, I haven't detected there flex.

After the initial idea it was one evening of drawing and another in making. I didn't finish it at all, because I was convinced that it was a prototype, but to my surprise it worked! I also reasoned that the blade could be deeper to allow cutting of larger diameter, but the lathe does not seem to rigid enough for any larger on steel and that was the blade I had in hand.
Metal Stuff / Re: New lining for the iron furnace
« Last post by awemawson on January 21, 2022, 03:15:22 AM »
Casting sand grain sizes are not logical Iím afraid when you compare the surface finishes on the castings. Certainly with iron quite coarse sands can give a surprisingly smooth finish due to the gas layer formed from the crushed coal.

Thereís quite a bit to it, permeability, refractory quality, surface finish, cohesiveness, ability to release the pattern and of course availability!

Artificially chemically bonded sands such as the phenolics and sodium silicate raise a whole new set of variables but are more predictable ( but have the disadvantage of not being reusable)

Towards the end of my foundry playing about I went over practically exclusively to sodium silicate. The sand when the carbon dioxide has done its bit is very stable, and intricate patterns can be pulled with little chance of it all falling out when inverted. For that to happen with a greensand mould is very disheartening!

Metal Stuff / Re: New lining for the iron furnace
« Last post by vtsteam on January 20, 2022, 06:50:27 PM »
Nope, no vacuum pump, Andrew.

Spread it out today for another few hours, turning it every once in awhile. Down to 6% now. Starting to feel a little better in the hand, but still too damp, yet.

I did some physical measurements, out of curiosity with a micrometer of various sands I have. The first was my aluminum and zinc molding sand -- which I've used for many years. I did several samples and averaged them -- surprisingly they were all quite close. This measures the largest average grain size -- it isn't a uniform sand. I rinsed all clay (hawthorn fireclay) off to do the measurements. It worked out to .012" or a #50 screen.

I then measured my ceramic grade quartz sand, which seems very uniform, also rinsing off the clay (bentonite) and it worked out to .010" or #60. Which confirms what the bag it came in said.

Finally I measured some "Fine" masonry sand purchased bagged at a local building supply store. It also tested out at #60. No idea how refractory it is as I've never tried it or mixed it with clay. But I'd like to try it with fireclay and see how it compares with my old aluminum greensand.

Interesting to find that my aluminum sand was so coarse. I thought it was up closer to #100 (.006") Several casting book authorities talk about #100 - #120 sieve for aluminum sand. Yet, my aluminum castings have always seemed to come out quite satisfactory, and better looking than most I see online. I did once try a bagged #120 blasting sand, but it had poor permeability, tended to short pour, and I ended up only using it for facing sand sometimes.

Anyway it was all something to do on a January day, indoors. High temps for the days will be well below freezing for the next week or so, and nghts around 0F with winds, so no casting yet.
Tools / Re: Rear parting toolpost
« Last post by appletree on January 20, 2022, 04:17:42 PM »
Good thinking out of the box
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