Thread: Spring steel precision blocks

I like to make my own stuff as much as possible and was wondering if spring steel would make ideal precision blocks? Was thinking of the heavier truck type springs, if they were suitable. I know that they are supposed to be hardened, but it's only a thought at this stage.
Thanks in advance
Kryn

Do you mean 1-2-3 blocks or gauge type blocks?
Regardless, spring steel (although there are alloys as well) is in it's most basic form a high carbon steel, so for something that sits there it is fine.
I would have though that truck springs had a little bit of heat treatment - whenever I've encountered leaf spring material it does not appear in a soft condition

Michael

Gauge type blocks, sorry forgot to mention that, already have a set of 1-2-3 blocks.
Kryn

You want to make accurate gauge blocks?

Good luck!!!

I'd suggest the type of steel chosen is the least of your concerns. Accurate gauge blocks are lapped extremely accurately so they will both wring correctly and to the specific size. If they don't do either of the above they're not gauge blocks. Given how inexpensively they can be obtained, either used, or from China, I'm not even sure why anyone would even want to create a set of DIY gauge blocks.

Hi Kryn,
In one sense you are wasting your time and effort. But its down to you what you would call a successful result and its your time and effort to do with as you wish. If you think you're going to turn a truck spring into a 112 piece set of sub micro gauge blocks, I'd say you'll be pushing it up hill with a long pole. Though I have thought about having a lash at making one(block that is not set) just for the exercise. Gauge block length should be known to an accuracy I cant even pretend to measure let alone actually measure. For e.g. a grade 2 10mm block should be something like +/-0.6 micron, parallelism 0.30, flatness 0.25. You'd then like to know the deviation known to 0.01 micron.

If you want something pretty close that will wring? I'd put that in the tricky but possible, and you're bound to learn a lot along the way. Something pretty close that wont wring? doable. but calling either gauge blocks might be pushing it, maybe "spacers" would be a better choice?

So, what would you call "close enough" and how big a set to you want?(they likely wont be stable over time, but that will, I assume, be in the ranges below what you are trying to get to).

Stuart

Thanks Stuart, Michael and Pete F, I was just thinking about making a couple of "spacers" as you called them. I didn't realise that they went that fine in tolerance and finish.
Jeez, I've got a lot to learn, just as well there are knowledgable people on here, to guide us poor unknowledgeable souls.
Would spring steel still be OK and as durable as tool steel?
Kryn

No alloy steel that I am aware of can get as hard as plain carbon steel.

If you could find some bisalloy and machine it, it would be suitable I think, but it will not machine easily with HSS in my experience.

Richard,
would bisalloy be particularly good for paralles or 'spacers'? Bits are relatively easy to get here in Bendigo, as the defence department sold off masses of the stuff for scrap recently.... much or all of the bushmaster hulls are made of it, as I'm guessing are most armoured vehicles.

Just for information, any "spacers" I make are just plain mild steel. I inherited a whole bunch of parallels that are hardened and ground (many of which I've now reground and matched), but any I've made myself are just strips of steel accurately ground and not hardened in any way. For the amount of use they get in the typical home shop, I'm quite happy with that choice of steel. Indeed it I didn't have the surface grinder I would just mill parallels and chances are they would be accurate enough for most work.

Should you really want to have hardened parallels, personally I'd look at finishing them and then surface hardening them. The latter doesn't introduce the same distortions as taking high carbon steel, hardening it, and then grinding it to size and finish.

Stuart quite rightly pointed out the difficulty in getting a surface that is good enough to wring. I personally think it would be entirely possible to lap a surface to that finish in a home shop such that it would wring, but not to the dimensional and geometric accuracy of a gauge block, not even close. Just measuring these suckers accurately is difficult enough and it's done under very controlled conditions (normally by comparison with a known standard).

I think this was put up here recently. By chance I was cleaning up my desktop on a computer today and noticed it saved there (now deleted). It should provide more information. By further coincidence, my gauge blocks are actually genuine "Jo Blocks" so I can use that bit of American slang in all truthfulness! http://www.mitutoyo.com/wp-content/u...Gage-Block.pdf

Hello Kryn,
Some time ago I bought a bundle of key steel when a machinery dealer was having a clear out. There were several dozen lengths from say 8mm to 25mm, and similar in imperial, all about 300mm long. For my less critical applications I find they are close enough in dimensions and flatness to be used for milling setups, and I wonder if it would be worthwhile to look for these and check sizes to see if they suited your purpose. Never know your luck.
Combustor.

Originally Posted by KBs PensNmore

Would spring steel still be OK and as durable as tool steel?

Originally Posted by jhovel

Would bisalloy be particularly good for parallels or 'spacers'?

You want something that will be durable and not damage easily. The harder the steel, the less likely it is to be dinged, dented or damaged in use and more likely to be dimensionally stable long term.
Both Bisalloy and truck spring will be stable so would do the job. How easy it will be will depend on the level of precision you are shooting for. The technical difficulties of producing an accurate* set of blocks in say 0.1mm increments are not small. Producing a set of blocks all the same size but not to an exact dimension is much easier.

Michael
*that's accurate in a metrology sense

Originally Posted by Pete F

Should you really want to have hardened parallels, personally I'd look at finishing them and then surface hardening them. The latter doesn't introduce the same distortions as taking high carbon steel, hardening it, and then grinding it to size and finish.

The surface hardening process must have improved out of sight in the last 35 years. I was centre grinding various cylindrical parts that had been case hardened back then and I would not even consider using a part that had not been ground due to the surface being quite uneven. It was a bit of an issue finding the right balance between how much to leave on the parts and how much had to come off to clean up at times.

Dean

Originally Posted by jhovel

Richard,
would bisalloy be particularly good for paralles or 'spacers'? Bits are relatively easy to get here in Bendigo, as the defence department sold off masses of the stuff for scrap recently.... much or all of the bushmaster hulls are made of it, as I'm guessing are most armoured vehicles.

There are many different grades of Bisalloy. There is an armour grade, no idea if it is machinable. You would have to look up the Bisalloy website.

Originally Posted by Oldneweng

The surface hardening process must have improved out of sight in the last 35 years. I was centre grinding various cylindrical parts that had been case hardened back then and I would not even consider using a part that had not been ground due to the surface being quite uneven. It was a bit of an issue finding the right balance between how much to leave on the parts and how much had to come off to clean up at times.

Dean

Yes but how were the parts finished before grinding? Commercial parts that are intended to be ground subsequent to hardening aren't normally finished to a high degree as to do so would be a pointless step in the process. The hardening I'm referring to is that available to the home shop. I use Kasenit (sp?) to surface harden mild steel when required. In my experience the finish is pretty much the same after the process as before. Maybe if I were to really look and measure carefully there could be a difference, but once the scale is polished off, for all intents and purposes the surface remains unchanged. The case, while quite hard, is however nowhere near as thick as would be typically achieved with commercial case hardening. I doubt it would tolerate grinding, although should be able to be lapped. Although every case is different, excuse the pun, I would typically use case hardening over full hardening for most occasions I need a hard surface. About the only exception is for cutting tools, where I'll always use carbon steel (or HSS etc).

As mentioned I typically don't harden my tooling unless it's actually required, and definitely wouldn't bother for something like parallels or "spacers". In my opinion some people are overthinking the whole area and could introduce further complications for themselves later down the track. If you harden something like this, while it's definitely true that it will withstand more abuse, it also means if/when it does get damaged you don't have many options to refinish it apart from grinding/lapping. If you have a grinder, that's great, go nuts, but not everyone here has that luxury.

Originally Posted by Pete F

Yes but how were the parts finished before grinding? Commercial parts that are intended to be ground subsequent to hardening aren't normally finished to a high degree as to do so would be a pointless step in the process. The hardening I'm referring to is that available to the home shop. I use Kasenit (sp?) to surface harden mild steel when required. In my experience the finish is pretty much the same after the process as before. Maybe if I were to really look and measure carefully there could be a difference, but once the scale is polished off, for all intents and purposes the surface remains unchanged. The case, while quite hard, is however nowhere near as thick as would be typically achieved with commercial case hardening. I doubt it would tolerate grinding, although should be able to be lapped. Although every case is different, excuse the pun, I would typically use case hardening over full hardening for most occasions I need a hard surface. About the only exception is for cutting tools, where I'll always use carbon steel (or HSS etc).

Generally the parts were centreless ground prior to hardening to a tolerance of 0.0005" if I remember correctly. This would vary a bit depending on size and wall thickness of course. What was done this way was mostly gudgeon pins for inhouse use. At one stage we made the pin for the timing chain tensioner for Mitsubishi Motors. This was the bit that acted as a piston/ram operated by the oil pressure. They were thin walled, but had a solid end for the plate to be pressed on for the rubbing block. They caused quite a bit of trouble. Cracking, not cleaning up. Very touchy.

Dean