Terranova wrote:The zero point is reached when the burrs touch each other, so if the grind setting has not been reached, than you are below zero and have a reason to be worried.

The burrs would have to be WAY WAY out of alignment to touch before you reached the typical grind setting on an HG-One. Even though my burrs were out of alignment they didn't make actual off center contact until well beyond the normal grind area.

here's my attempt to measure rough effect from paper shim of 0.02mm thick, the grinder is in perfect alignment before the shim. not really sure if my measuring point is proper or process is correct though here it goes..

it's bit confusing as the model is facing -x axis, huh, sorry I'm on small laptop screen and no mouse. anyway on each image, top left is top down view, (grinder handle is on posX side, screen right) bottom left is side view, same here, grinder handle is on screen right. ignore bottom right section that is front view which from that direction you can't change anything meaningful without mod I believe.



placement of paper shim : measured distance diff from bottom, center of lower burr : rotation of assembly from shim


A: top of gear box : 0.032mm : 0.013' ver


B: btm of gear box : 0.05mm : 0.013' ver


C: left side of gear box : 0.027mm : 0.022' hor



D: top of burr mount assembly : 0.059mm : 0.052' ver


E: btm of burr mount assembly : 0.062mm : 0.052' ver


F: left side of burr mount assembly : 0.02mm : 0.015' hor



I should have measured the change from the edge of the burr, but I guess the number itself doesn't mean much here, just relative direction burr mount moves and the distance. of course for A,B,C direction is for upper burr, and D,E,F the lower.

- Arnold

This post is just to be clear on how to check your burr mount (i.e. burrs) are in alignment, since nobody actually mentioned it.

You will have to take out the inner and outer burrs. Then attach a dial indicator to the screw mount at the bottom of the shaft so that when you turn the shaft you turn the dial indicator. Then measure (with the locking screw tightened) the runout of the inside of the outer burr mount. You can't ask for anything much better than .002". I pulled this number from a thread with Frank, but I don't have experience doing this.

It would be like in this video [youtube]http://youtu.be/VY2crpjhL3E?t=4m[/youtube]. Imagine the indicator attached to the HG-one shaft coming through that tube and bent back down measuring the same spot (dial indicators come with long arms that can move around). You may want to measure the bottom to make sure that it's level with the rotating shaft.

As for adjusting the HG-One you could use paper shims or tin foil or something of the sort. If it's out of alignment side-to-side, you can just tap the burr carrier over a little bit if there is slight play.

TL;DR Long story short, measuring your runout is a huge pain and you will likely have to fabricate a holder for your dial indicator to attach to the shaft. Even if you measure it, there may not be much you can do about it - or it may be in alignment. I think the HG-one has earned it's place as a capable grinder, I think folks should only worry about this if they are espresso grinder design hobbyists or machinists.

The digital camera idea is a good one! Measuring pixels can be very accurate, why didn't I think of that!!!

It makes absolutely no sense to disassemble the grinder to verify if burrs are properly aligned. Only disassemble it if you need to recalibrate it.

To answer Rich's question, my espresso setting is almost a full turn from zero-point. And from my espresso setting, if I just tighten the grind by an inch or so clockwise, it'll choke the shot.

Below are a couple of pics of the grind that is produced near zero point . To the touch the grind is baby powder-like. Silky smooth. So fine in fact you can leave finger print impressions in it.



Here's the exact steps for checking your alignment:

1) First you need to flush any residual grinds from the burrs. I use compressed air as well as rotate the crank wheel forward and backwards several times until it feels completely free of resistance..

2) Then loosen the burr lock knob just enough and slowly adjust the burr mount clockwise until the handle moves from its resting position.

3) Tighten the burr lock and try to clear more grinds.

4) Repeat steps 2-3 until the burrs are as close as they can be without touching. This is your "zero-point". If you have a funnel wiper, make sure to remove the lower funnel (otherwise the wiping sound will be mistaken for burr rubbing sound you're listening for). Anyway once you find your zero-point setting, make sure the burr adjustment lock knob is nice and tight.

5) Drop in 3 or 4 beans and grind--the gap between the burrs will be very small, so there will be lots of resistance getting the grind going. I recommend you secure the grinder with C-clamps if you can not keep it stable while grinding. Keep a very close eye on the burr mount as you start grinding to so as to stop if the burr mount slips. If it does you'll have to start over and clear the grind again. Make sure the adustment lock knob is adequately tightened. Assuming all went well, if your burrs are properly aligned, the grind should be very, very fine, like the above pictures.

JohnB. wrote:The burrs would have to be WAY WAY out of alignment to touch before you reached the typical grind setting on an HG-One. Even though my burrs were out of alignment they didn't make actual off center contact until well beyond the normal grind area.

Same here. I used old paper between burr trick to check the alignment. For adjustment, I had the screws for burr mount and gear box little bit loosened but still tight, make the grind fine enough so paper between burr creates friction where gap between is tighter (lock the burr after grind adjustment). use rubber hammer tap on either gear box or burr mount to correct the error, etc etc. once I reached the point I can no longer compensate with hammer tap, paper shim has been used, and repeat with shim in place. I ended up using two printer papers on gear box and one on the left side of burr mount.



before there was fine grind clogged at the bottom of basket after the shot, and compare to the extraction, flow rate was too slow. I'm not an expert but to me feels like my shots looked way under extracted but still had very aggressive taste sametime with under extracted tone. I guess relatively small fines clogged the bottom and rest of the grind was too coarse probably the issue was from misalignment.

Anyway after the adjustment, I don't get fine layer clogged in basket bottom, also taste got much much smoother and extraction looks a lot better.

- Arnold

Great responses everyone. Seems like everyone who took the time to finess the burr alignment had positive noticeable results.

Took a piece of paper to find out if the inner burr was properly aligned. At one corner it got stuck and all the rest it ran freely. Used small plastic chip on one corner of the gearbox. After a couple tries using different thicknesses and positions, found the best possible alignment.

Now my espresso range is about half a turn tighter on the adjustment ring.
Grinds look a bit fluffier, more uniform. Experiencing less static. A slight improvement in taste, although it's more of a 'change' than an improvement. Hard to grasp, but almost seems smoother, more balanced, some piercing notes have disappeared, but depends on the bean used. Difference is more profound with lighter SO roasts and less noticable with dark Italian blends.

Edit: Also added copious amounts of Dow 111 to the burr adjustment thread, now movement of the burr during locking is invisible to the eye.