Printing another Hoffman Tactical but this time a 308 lower.  Just went and checked on the print and noticed what looks like a pretty clear shift in the print.  For those with more experience than I and those that own Hoffman Tactical 308.... is it supposed to look like this?  Should I stop the print and start over (it's at 50%)?  Will it be ok and just let it finish??

The mistake/shift is about half and inch from the top in all the pics.

Thanks!!

Can happen when you have something like a belt slip or a stepper motor miss some steps.  Or if you're printing over USB/wifi, a hiccup in the computer talking to the printer.  I prefer to print from SD card on the printer rather than streaming the print line by line.

If anything, that would make your magwell a little tighter.  It may make some magazines not fit or maybe not drop free.  I'd at least let it finish printing and test fit to see that everything else fits like it should.

Oh ok.  I'll let it finish.   But now it looks like it shifted back another half inch up.  I'll post picks when it's done.   Never had this happen before.

What makes the printer do this?  Is it an indicator some part is starting to go?  

I always print from micro SD

Thanks

Could be so many things that it's hard to say. Unless it repeats the shift at that height every time you'll never narrow it down. Just give the printer a once over and try again.

Finally finished.  The mag does insert but it's so tight, it almost gets stuck.  I'm going to start another one today but I'll keep this one and see what leverage does to help functionality (so having a stock and upper attached may make the wedging less of an issue.  But if it is too difficult to insert and remove, I'll chuck it and just hope for a better result with the next one.  

An unrelated question....I know the slicer gives me how many grams of filament will be needed.  How do you estimate accurately whether you need to switch out a roll vs. keep the one that's already being used for a given print?  

Thanks!

EDIT:  Something else I'm noticing is, before even getting to the shifted part, the mag is struggling to go in.  I'm using LR/SR 20rd Pmags.  It will insert with muscle and then gets stuck in place.  And can be me muscled out.  But yeah....the well seems too small.....advice??

Have you done calibration prints on your setup?  Design and print a 10.00mm cube.  Then measure it and see if your printer is doing over or under sized.  Even if the xyz movement is dialed in, printers can still print oversized if the extrusion is cranked up too high.  And that number can change depending on your amount of infill.  For example, if you are over-extruding just a tad, but there's not a lot of infill, some of that extra plastic can end up in the voids inside the model where it doesnt matter.  But with 100% infill, there's no room inside, so the extra plastic ends up on the outside of the walls, making any holes like your magwell smaller.

As far as calculating your filament, it helps if you keep track of how much you've already used from the roll.  But thats not an exact science because the weight per distance is not constant.  Sometimes filament will have high and low spots.  Supposedly the pricier filaments are more consistent.  Your printer doesnt print by weight.  It prints by distance.  The extruders spit out so many millimeters of filament.  Whether or not they hit fat and skinny spots in the filament along the way doesn't matter.

Which makes it harder to be accurate.  They sell filament by weight, not distance.  But printers print by distance, not weight.  You do whatever you can and just factor in some wiggle room so you're not trying to print right up to the last cm on the roll.  Or else you learn how to splice filament and you just watch the printer.  When it gets to the end of a roll, cut it and splice it onto the new roll.

Thanks for the info.  Printing a 100% infill 20mm calibration cube now (since most important prints are done at 100% infill).  We'll see how it turns out and if it's anything other than flawless I'll share pics and we can go from there with any adjustments needed.

Thanks again!

Some manufactures also provide the empty weight of the spool, or you can find the weight online somewhere.  Then weigh the spool in question, and subtract for the difference.  That'll give you the weight remaining, but like mentioned, it may not be exact when the slicer/printer converts to length.

I weigh the new spool before I print and write on it the weight. Then if I use it again I weigh it then I know how much filament I used.

Did the layer shift effect anything behind the magwell?

If the only thing you're seeing as a problem to build is the tight magwell, I'd try filing it to open it up.

I've done that with aluminum lowers that had tight magwells.