I thought I would take a few minutes to share some of my experiences using a manual Hario Slim Mill grinder for espresso, in case anyone else has entertained the idea. There are some older posts that discuss the topic, but I'm not asking a question so much as discussing my thoughts on feasibility.

I have used the Mini Slim as my primary grinder every day for around 3 months and I've learned a lot from it. To give a small amount of background, a few months ago I was given the opportunity to purchase a well cared for, used, Rancilio Silvia at a great price - but it was all of the money I had saved for espresso at the time, which meant no high end grinder to go along with it. Rather than waste the money on a low-mid end grinder, I figured I would shell out the $20 for the Slim and see what happens while I saved more.

The first thing you'll notice when grinding with the Slim for espresso is that it takes a very long time. If you're grinding by hand, it can take between 5-10 minutes, depending on how tired you get. I put it that way, because I didn't grind by hand for long. I quickly learned that many people had taken to grabbing their cordless drill, and fitting it on the end of their Hario. Personally, I was able to simply tighten the chuck around the input shaft (it's a 5-sided head, so it won't take a standard hex socket).

Grinding with the drill is a mixed bag. The process goes faster, but you have to keep a few things in mind:
-Go slow or the grinder will heat up and quality will suffer.
-I found a 2-3 minute grind time (for 18g) was a good balance between speed and quality.
-The noise of a cordless drill is much louder than most grinders, especially while going for that long.
-WDT is a must since all of the grinds get compacted in the bottom of the catcher. However, it makes a huge difference in quality.

The greatest drawback of the Hario is that its steps are very coarse, which means that only 2 of the steps are really feasible for espresso. Occasionally, you get lucky and one of the steps corresponds perfectly with the bean you have, but more often than not it's a combination grind, partially on one step, partially on the next. This can be extremely frustrating, and I think that frustration is something to keep in mind when making product selections. People tend to undervalue the user experience, and overvalue features and price.

A week ago I was finally able to score the deal I was looking for on a Mazzer Mini-E, so I now have something (other than my local cafe) to measure up against the Hario. I have to say, I was surprised to find that the Hario really isn't all that bad, particularly when you get lucky with the steps on the grinder. That being said, I'm still getting used to the Mazzer and I'm sure I'll see a greater difference in the cup as I go.

Long story short, you can occasionally get good to very good espresso out of a Hario Slim Mill, but it takes a lot of luck, even more patience, and a ton of frustration in between. However, I would wager that grind quality may even exceed some of the other electric grinders out there in the $200 range and below, even if the user experience is inferior. If your on a budget, my advice is to buy an Aeropress and wait it out until you can get both a machine and grinder of solid quality. My passion simply outweighed my lack of patience, so I was able to stick it out for a while

A quick footnote to frequent posters on HB: Thanks a ton for all of the contributions you've made, I've been reading the site up and down for the last few months and I've learned a ton. I appreciate it and hope to give a little back in the coming years as I learn more!

You can make the Hario Slim stepless, which will help. You'll need a posilock/nyloc nut to replace the stock lock nut. An M8 or M6 depending on if you're using a Skerton or Slim. Then you need a small wrench to adjust the nut. If you consider 12 o'clock true zero, espresso range will be roughly around 630 or 7 o'clock...if I remember correctly.

I used a stepless modded Hario Slim a few years ago with a Mypressi Twist when I first started home espresso. So it can be done. But it's far from ideal and requires a lot (a lot of frenetic!) manual grinding, as you discovered.

Here's a link to what mine looked like:
Best grinder for espresso, budget around $300

That's a great link Ryan, pictures are always clutch. Stepless is an absolute necessity, and I really think it's not half bad once you get over the stepped limitations. There's a good chance that my Hario will live at work once I get a Mypressi or Aeropress for something decent to drink at the office.

Thanks for the response

No problem!