Review of Hemingway Sensitive Knurler Kit

[rronald]

I purchased the Hemingway Sensitive Knurler kit about three weeks ago. Thought I’d write a review, since there were many things that I liked and several that I did not.

The shipping to the USA was a bit expensive, but exceedingly fast. I ordered on the 16th of July and it was delivered on the 20th.

In the kit, you get some nice drawings and metal stock. Rectangular pieces and rounds that are cut to the required length plus an inch or so.

Pluses:

• I’ve learned a lot about making parts. And about messing up a few of them.
• I’ve acquired quite a few new tools (slitting saw, boring head, collet blocks)
• It seems like a good design. I just finished the last hard/new operation and expect to be done soon. I may have to remake a few parts to make everything work to spec. But I know how to make them now, so it won’t be a problem.

Minuses:

• I found the kit to be much harder than I expected. Some may consider this to be a plus.
• Many of the raw stock dimensions are a tiny bit undersized. I found it hard to tell if this was going to be a problem (see minus # 3 below).
• There are no instructions included to tell you how to make the parts. For someone relatively new to machining, a bit more information would be useful. However, some may consider that figuring out how to do the operations is good; i.e., a useful/positive exercise. In the absence of detailed instructions, there are several well-done videos available on YouTube (search on Hemingway Sensitive Knurler + Youtube)
• There are no tolerances provided on the drawings. Coupled with undersized raw stock, I found this to be a major aggravation. Should I shrink the hole because the pin is smaller than the nominal diameter (there’s also no guidance as to whether you should be aiming for a slip fit or a press fit)? Should a shoulder be exactly the right distance away from one edge on a part that’s a few thousandths short of the stated width or does the shortfall get taken from the other side? Or maybe, I should bring both edges in by half the shortfall?
  
  I worked for a short time as a drafting/machinist apprentice in the late 70s. It was a long time ago, but I clearly remember that every dimension had a tolerance. Most of the dimensions on the drawing had an upper limit printed above a lower limit. Anywhere in the range was acceptable. Some of the measurements were addressed by notes on the page providing a “default” tolerance. But, if there was no tolerance that could be ascertained for each and every measurement, the drawing was wrong. The part would be considered un-machinable and would be returned to the draftsman.
• The kit drawings often show metric and imperial measurements. But they often aren’t exactly the same measurement (e.g., 3/8” vs. 9.5mm). That’s pretty close (10/1000ths off), but it’s not always obvious that it’s close enough.
• The kit mixes measurement systems. There are threads specified in metric. And in imperial, And in BSF.
• There’s no upfront guidance available on the Hemingway site about the tooling you need to make the parts. I should have been more diligent and found the YouTube videos before ordering and that would have told me that I probably needed a lot of tooling that I didn’t have:
• A square collet block
• A boring head
• A rotary table ( made do w/o this)
• Slitting blades and arbor

If I could travel back in time, would I buy the kit again? The answer is probably yes. Not so much for the knurler, but it was good to have something that forced me to add several new techniques to my repertoire. However, if I could find a kit with proper dimension tolerances, it would undoubtedly be a more pleasant build.

 

[GrifterGuru]

This is timely!

I was considering this kit as a project, but now, I think I will see if I can just get the set of drawings and supply the materials myself.

 

[woodchucker]

There’s no upfront guidance available on the Hemingway site about the tooling you need to make the parts. I should have been more diligent and found the YouTube videos before ordering and that would have told me that I probably needed a lot of tooling that I didn’t have:

There is no need to tell you every tool that you will need. Some will do it with bare essentials, others with less. And many will buy every possible tool and possibly never get it done.
There are many ways to do something. I am always amazed by @savarin who will make many things with only a lathe, no mill. He is proof that it can be done. Watch some youtube of guys making with an angle grinder, hand drill, file, (no vise) etc. And they make things, working on the floor.

We all like tools to make the job easier, but many have shown, they can make their own dedicated tool to get a particular job done.

So in conclusion, you don't need the tool, you need to think how YOU can get it done.

As far as undersized raw material, and no hint of tolerances... those are valid concerns. The mix of metric, imperial and bsf is also a valid gripe. There should not be a need for that. Standardize or offer measurements for each variation (but stick with type).

Also how to is up to you. Not up to them. It's based on your tooling, and your way of working. That's part of machining, and doesn't allow you to grow if they tell you what to do. @Tony Wells had a great signature
"A man who works with his hands is a laborer. A man who works with his hands and his brain is a craftsman. A man who works with his hands, his brain and his heart is an artist."

-Louis Nizer

 

[ChazzC]

This is timely!

I was considering this kit as a project, but now, I think I will see if I can just get the set of drawings and supply the materials myself.

IIRC you can buy plans only, but only as hard copies, not pdf’s - not a problem for you since you’re “local.”

They are also good at answering questions: I was considering buying a Centering Scope kit (just because), but was concerned about the level of difficulty - they said while it might challenge the capabilities of a 7x16 lathe I should be able to complete the kit. In the end, the delivered cost and the fact that it would only be an exercise in fabrication I decided I didn’t need to add another seldom used tool to my shop.

 

[SouthernChap]

Many of the raw stock dimensions are a tiny bit undersized. I found it hard to tell if this was going to be a problem (see minus # 3 below).

Honestly, I'd have emailed Hemingway in that case.

I mean if one bit of, say, 80mm, 10mm dia. round stock turned out to be 9.90mm, but everything else was at or over-size, I'd just source a new piece of actually 10mm dia stock.

But if there were multiple bits of stock that appeared to be under-size, going by the drawings, I'd first check I'd read the drawings properly and then, once I'd confirmed I wasn't just being daft (and to be fair, that's a fairly common occurrence with me!), I'd contact Hemingway.

If the stock was undersized, Hemingway have (inadvertently, I'm sure) sold you something not of merchantable quality and they should offer a replacement or a refund.

You didn't just order the drawings, you paid for the necessary stock to complete the kit with. You didn't get what you paid for.

 

[GrifterGuru]

Honestly, I'd have emailed Hemingway in that case.

[snip][/snip]

If the stock was undersized, Hemingway have (inadvertently, I'm sure) sold you something not of merchantable quality and they should offer a replacement or a refund.

You didn't just order the drawings, you paid for the necessary stock to complete the kit with. You didn't get what you paid for.

Quite!

I would do the same (email first, then telephone and direct them to check the email) and yes, perfectly true about the merchantability of the kit with undersized stock and not getting what you paid for.

 

[SLK001]

This is my version of the knurler. It is based on the patented Marlco knurler. I created my own drawings. What you purchased were the drawings and instructions. You got raw stock as a courtesy. It is up to the machinist to determine if the stock is adequate for the task, or if it needs to be acquired elsewhere, or if mods are needed to the drawing. A kit like this isn't like a Revel aircraft model, where you just clip off a part and glue it together. Studying the design and comparing it to your materials and making the needed adjustments will lead you to a successful project. I agree that the material should be as specified, but this isn't a perfect world. I'm glad that you were able to adjust the design to the available materials and have a successful outcome. Welcome to machining!

I had to do the above adjustments here, too. My 3/4" stock was more like 0.725". These adjustments need to carried all throughout the design. Fortunately, I purchased O1 rounds for all round pieces and they were spot on! When a project like this is completed, just remember to purchase quality knurling wheels for it. They make a world of difference.

All the convex curves were done on a belt sander. The concave curve was cut on the lathe. I designed the capacity to be 4". For the wheel holder, I recommend that you simply use a press fit, instead of the kit's elaborate design.

 

[craniac]

I appreciate the review, as I have had one of these kits on the shelf waiting its turn. If the plans lacked detail why not reach out to Hemingway? Are they responsive?

Tim

 

[rronald]

I did not contact Hemingway, so I can't speak to their responsiveness. Might have been a good idea.

I'm relatively certain that the slightly undersized raw stock that they supply can be turned into a great knurler. If they'd provided tolerances, it would be much easier to succeed at that task.

As for the level of instruction, I fully agree that it's perfectly valid to force the builder to figure everything out. However, it would also be valid to provide guidance about the recommended tools and processes. The cost and benefits of both approaches would tend to appeal to different types of builder. The kit failed to match my expectations, but that doesn't make it bad. It just makes it unexpected for me.

Hence, my review.

 

[SouthernChap]

This is my version of the knurler. It is based on the patented Marlco knurler. I created my own drawings. What you purchased were the drawings and instructions. You got raw stock as a courtesy. It is up to the machinist to determine if the stock is adequate for the task, or if it needs to be acquired elsewhere, or if mods are needed to the drawing. A kit like this isn't like a Revel aircraft model, where you just clip off a part and glue it together. Studying the design and comparing it to your materials and making the needed adjustments will lead you to a successful project. I agree that the material should be as specified, but this isn't a perfect world. I'm glad that you were able to adjust the design to the available materials and have a successful outcome. Welcome to machining!

I had to do the above adjustments here, too. My 3/4" stock was more like 0.725". These adjustments need to carried all throughout the design. Fortunately, I purchased O1 rounds for all round pieces and they were spot on! When a project like this is completed, just remember to purchase quality knurling wheels for it. They make a world of difference.

All the convex curves were done on a belt sander. The concave curve was cut on the lathe. I designed the capacity to be 4". For the wheel holder, I recommend that you simply use a press fit, instead of the kit's elaborate design.


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I don't know who your suppliers are in your day to day job, but I suspect most companies would look askance at a supplier who sent them out of spec materials. When I worked at Cosworth, if we paid for aluminium ingots or mould sand, we expected to get what we paid for.

Hemingway explicitly state:

The kit includes all necessary material for the tool itself (without knurls) together with drawings and construction notes.

The materials are not there as a courtesy. They're part of the product; what the OP paid for.

That the OP worked around the defective supplied stock is to their credit; not something the buyer should have to do.

So with respect, you're talking bollocks!