MakerFarm 8" i3v Prusa build by Printbus

[RaySuave]

how long should it take the bed to get up to 110 temp using the relay, seems really slow. so far 27 minutes to heat the hotend and then get the bed to 78 degrees.

I got the 10" i3v with the relay and it only takes about 4 minutes for the hotend and between 10 - 15 (110) minutes for the bed. I take the hotbed to about 106 because the bed struggles to keep a 110 temp. If you have any air blowing over these parts, they will take a lot longer to heat up.

[Roxy]

EDIT: I should probably note that my hex hot end is not running the original cartridge heater, aluminum block or thermistor. I use silicone heatsink compound on the cartridge, and my hot end aluminum block is insulated on all sides with kapton tape. My hot end warm up time may not be comparable to the usual config.

I tried this and the heat sink grease I used ended up drying out and getting crumbly. Did I just use the wrong grease?

[usarmyaircav]

That's a long time. For comparison, my hex hot end goes from room temp to 215 degrees in about 90 seconds and the 8-inch heat bed goes from room temp to 110 degrees in about eight minutes. Some suggestions on things to check -

• Make sure the power supply output stays at 12V when the heat bed turns on
• Make sure any screw terminals at the power supply and heat bed relay are tight
• Make sure the heat bed thermistor is secured well to the bottom of the heat bed (no gap)
• I'd try to make sure cardboard or other insulator you're using between the Y-bed and heat bed isn't pressing against the heat bed thermistor. If the insulator is touching the thermistor, the thermistor won't be properly reading the heat bed temperature. Cut a clearance hole in the insulator if required.

Beyond that, I'd suspect the gauge of the wiring used with the heat bed is on the small side, and you're not applying the power you could be to the heat bed. You could verify this by measuring what voltage is actually applied at the heat bed itself. Do you feel any of the heat bed wiring getting warm? That would be another sign of power being lost in the wiring. As I understand it, the 10-inch heat bed can draw as much as 18 amps. As heavy as 12-gauge wiring might be appropriate for that much current. Can you read the markings on the wires that came pre-attached to the heat bed? One thought would be to use at least the next larger size for the fixed wiring between the power supply and the heat bed relay where flexibility isn't important.

EDIT: I should probably note that my hex hot end is not running the original cartridge heater, aluminum block or thermistor. I use silicone heatsink compound on the cartridge, and my hot end aluminum block is insulated on all sides with kapton tape. My hot end warm up time may not be comparable to the usual config.

What I found out is that the wire I used from the PS to the relay is not the right gage. It was way hot, so I shut it down. I will make a run to Lowes tonight to get some 12gage wire. It was after I had posted this that I decided to check for loose wires and when I grab the wires coming in to the relay it was like "wow is that hot" Thankful nothing seems to have melted down.

[printbus]

I tried this and the heat sink grease I used ended up drying out and getting crumbly. Did I just use the wrong grease?

It's hard to say. If the compound was metallic in color, I believe drying out is what is intended - improving the bond of the remaining silver-laden part. The problem with that is any mechanical movement breaks the bond and the compound has to be cleaned off and reapplied. I used the old school white grease that seems to never dry out. Just a bit along the edge that the set screw will push against the block.

[printbus]

What I found out is that the wire I used from the PS to the relay is not the right gage. It was way hot, so I shut it down. I will make a run to Lowes tonight to get some 12gage wire. It was after I had posted this that I decided to check for loose wires and when I grab the wires coming in to the relay it was like "wow is that hot" Thankful nothing seems to have melted down.

Another option for you would be to double up on smaller gauge wires.

[usarmyaircav]

Another question I have is it seems like the spool holder rubs on the makerfarm filament roll, enough that I am pretty sure it isn't going to turn by being pulled from the extruder. Thoughts?

[gmay3]

It should be fine as is. If you want to reduce the friction slightly try this: http://www.thingiverse.com/thing:326641

[usarmyaircav]

It should be fine as is. If you want to reduce the friction slightly try this: http://www.thingiverse.com/thing:326641

I should have clarified, that it seems to be rubbing on the sides at the bottom of the spool, because mine seems to be narrower at the bottom than the top, and there really isn't a way that I could have put it together wrong. (or so I think. )

On a side note, I have that thingi liked and saved in a collection.

[printbus]

Another question I have is it seems like the spool holder rubs on the makerfarm filament roll, enough that I am pretty sure it isn't going to turn by being pulled from the extruder. Thoughts?

I have three rolls of filament from MakerFarm - all three have different types of spools. Someone else reported that the filament they got from MakerFarm had a spool too wide to fit the spool holder. Is that what you mean? That would be a problem. Otherwise, something like gmay3's suggestion would help. At least one person is sure his extrusion jams/stoppages were due at least in part to the spool hanging up on the stock mount. Ray Suave has a thread showing use of a wood stick and bearings instead of the wood cross piece. I moved away from the stock mount when I was having stoppages, but I think my problem was ultimately repetitive retractions in the particular print I was working with.

EDIT: Posted before seeing the reply to gmay3

[usarmyaircav]

Printbus, you have it correct the spool is too wide for the spool holder. I will have to figure out how I can do this. My current location gives me no where to put the spool. I will have to consider where I can move the printer to, or another way I can mount it above the printer.