|Jed Martens||14/12/2019 08:49:03|
57 forum posts
I'm considering asking Santa for a set of slip gauges for Christmas. These will be for set-ups on the mill, checking the calibration of equipment, verify the accuracy of my work, etc. I think this means "workshop" grade (grade 2).
Are there any obvious pros/cons to look for?
If they claim compliance to some standard (eg: DIN861) can one consider the quality to be adequate?
Is 0.01mm resolution good enough, or are there reasons to go to 1 micron? My machines and measuring kit only go to 0.01mm...
Some of the sets I've been looking at...
Any advice gratefully received.
|Chris Evans 6||14/12/2019 08:53:56|
|1527 forum posts|
I spent 50 years in engineering and most "shop floor" sets where "workshop" grade. Only the very high end toolrooms I worked in had Inspection grade slips.
|448 forum posts|
I would look at ebay as sometimes you will find good deals if you look hard enough. I got a Vogel 32 piece set grade 1 in an almost unused rust free condition, for £55.
|1386 forum posts|
I purchased mine from eBay but I will admit to being nervous - as you really don't know what you are getting just from a photo of them sitting in the box. I was very lucky and my set is in very good condition (most will wring together). One of the set (88) was missing but by coincidence I spotted the required gauge the following week (a brand new Mitutoyo) for a reasonable price.
I do use them and (for the price I paid) I'm happy to own them. For most home workshops, they are not essential (you can find other ways usually) but they are a "nice to have" if the price is right. I think mine might have been inspection grade originally but they certainly won't be now. Not a problem - I doubt any home workshop would really need that level of accuracy - and the high cost wouldn't make sense.
|Kiwi Bloke||14/12/2019 10:12:19|
|275 forum posts|
'Any advice' requested. Well, it all depends...
If you want the slips to be your workshop dimensional standard, you need to be able to ascertain that they are dimensionally within specification and they need to function correctly, i.e. wring together. A non-wringing, old set, out of spec., can, however be very useful in the 'shop, for some tasks, but it should be very cheap. Tungsten carbide and ceramic sets don't rust, but they chip. Sets can be calibrated and reconditioned - at a price.
Buying unseen off the 'Bay must be considered risky. Buying new is also risky, if the unbranded set is 'certificated' by an unknown outfit in the Orient...
My advice would be to get a new set, from a reputable manufacturer. Start saving now. Or get lucky at a sale, where you can check the set for 'wringability' (although not for accuracy, unless you carry an interferometer with you...). Then, of course, to get your money's worth from the slips, you'll need all the ancillary gear - surface plate, indicators, indicator stands, micrometers, rollers, balls, etc., etc. Start saving more...
|5017 forum posts|
I've dithered around this one as well. Like Jed my measuring kit is only good to 0.01mm at very best; usually I work in the 0.02mm region, better only if it really matters. Is it worth me owning a Gauge Set, and if so what sort?
Fairly easy to dismiss are the Grade 0 and Grade 1 sets. Expensive and only worth the money if you are a tool-room or metrologist. In this range of accuracy, special care, calibration certificates, clean-rooms and temperature control may be essential. One thing to own a box of Grade 0 gauges, quite another to to use it properly!
Another type I can dismiss are the fancy Grade 2 sets made of ceramic or carbide. These are made to resist wear and tear in busy environments where they are frequently used. I'm not busy.
A new set has the advantage of guaranteed accuracy. The slips aren't worn, scratched, dirty or dinged on their edges. This means any combination of slips can be stacked together ( "wrung" ), and still be accurate. Rule of thumb for calibrating a measuring tool like a micrometer is that the standard should be about 10x more accurate than the micrometer. The graduations on a metric micrometer are typically 0.01mm apart and it's possible to eyeball half that, or even thirds. But if the micrometer is slightly 'out' at 0.01mm already (it probably is, because both instrument and operator are unreliable!), these estimates are unlikely to be trustworthy. By testing the micrometer against a gauge stack in good nick, it's possible to confirm whether or not the micrometer/operator combo are consistent, and more usefully suggest what corrections are needed. Beware, a decent set of gauge blocks may tell you all your tools are carp and/or that you're an incompetent operator! Good news for me, the number of times I've needed to work to this level of accuracy is zero!
You mention using the gauges for setting up on the mill. Perfectly reasonable if that means confirming the accuracy of a set-up, not a good idea if the slips are used for work holding. The latter is abuse sufficient to undermine the accuracy of the set. Much better to use parallels, blocks or whatever, and check them for accuracy by comparison with the gauges. The number of times I've needed to work to a level of accuracy requiring gauge blocks with my milling machine is zero! I'm a hobbyist, not a Swiss Watchmaker.
For me a brand-new set of gauge blocks is over-kill. I'm tempted by a second-hand set though. Most likely, these are available because they failed calibration because one or more blocks in the set is damaged. When 10x resolution is essential, they get dumped immediately by the professionals. But for ordinary workshop use 5x accuracy is often adequate, and 2x would meet my rough needs. This is an eyes wide open decision though. If you genuinely need gauge block accuracy, don't arse about buying unknown second-hand - buy new or insist on an up-to-date certificate! But if the goal is to cross-check relatively low importance workshop measurements, to be more confident in the 0.01mm region, then why not.
If someone gave me a new gauge set for xmas I'd be delighted. It's the sort of present I'd enjoy, but can't justify buying myself! I'd use them to find out the error margins of all my Digital Calipers and Micrometer. To do this properly the full range of the instrument has to be checked. There's no guarantee that an micrometer good to 0.01mm at 5mm will still be true at 20mm. Might get expensive, because none of my instruments are high-end. After finding out just how iffy they really are I might have to replace the whole lot with Mitutoyos or better!
Edit poxy smiley!
Edited By SillyOldDuffer on 14/12/2019 10:17:52
|Tony Pratt 1||14/12/2019 11:24:18|
|960 forum posts|
All the advice above is relevant & my bit is go for a new workshop grade set as it looks like you want to use them as a 'standard' which of course slip gauges are, so no point in buying 2nd hand worn jobs.
I would suggest using someone like Rotagrip, Cutwel or Cromwell tools as these are industry orientated suppliers so hopefully the standards they quote are actually adhered to in the product offered.
|jimmy b||14/12/2019 11:33:50|
561 forum posts
I've ended up with a metric and imperial set.
A slip gauge accessory set is very worthwhile addition, as it turns the slips into an extremely versatile measuring tool.
Well worthwhile investing.
|Glyn Davies||14/12/2019 11:37:22|
|114 forum posts|
I found limited use for slip gauges until I came across an accessory set at a car boot similar to this one that is on ebay:
I now use them a lot - it's so easy to make up various configurations of go-nogo gauges for jobs where it's difficult to get a mic or caliper into.
|Phil P||14/12/2019 11:39:43|
|576 forum posts|
I cannot help wondering just how many of us model engineering types actually own a set of slip gauges, and if they do own a set how often do they ever use them. ?
Personally I do own a set that came my way when my employer was chucking them out so they did not have to pay the annual calibration charge on them. The sad thing was that nobody had used them for many years !!. I actually acquired two sets and gave the other set to a friend.
I only really use mine when setting up accurate angles on my sine table, and the last time that happened would be around three years ago when I needed a spot on 22.5° angle for the eight flywheel segments for Agnes.
Depending on what you are doing, how much spare cash you have, and what other equipment you already have available, I would consider owning a set of slip gauges relatively low down on the priority list for general model engineering.
Just my 2p worth.
Edited By Phil P on 14/12/2019 11:40:46
Edited By Phil P on 14/12/2019 11:41:40
Edited By Phil P on 14/12/2019 11:43:03
|996 forum posts|
Posted with monotonous regularity, a screw jack and mics more than adequate for non NASA muddle ingineerin.
|A Smith||14/12/2019 12:19:32|
|33 forum posts|
I'd suggest that slip gauge sets come on the market reasonably frequently as the estates of model engineers are dispersed. I bought a set from the much-missed tool shop in Colyton, as with much of David's stock, it came from someone that had moved into care. I don't use it very often but find it useful on occasion.
|Ian Johnson 1||14/12/2019 12:45:19|
|215 forum posts|
I bought an old imperial set from a stall at the model engineering show for £30. I didn't need a set of slip gauges, it was a present to my self. I have used them for checking the tee slot gaps and key way slots, and they are regularly used to check my micrometers. They are the most accurate thing in my workshop, much more accurate than I will ever be!
Top tip! If buying second hand check for matching serial numbers, on mine they are all 414.
|448 forum posts|
No one is saying to buy a "worn" 2nd hand job. There are a lot of good deals out on ebay and similar. When in doubt ask the seller and if not satisfied just walk away. You'd be surprised how many tooling in brand new never used condition you can find if you look and ask.
Imo for hobby use the cost of £250 for a set of new slip gauges is not justified - if I were a business it would be another story.
|Tony Pratt 1||14/12/2019 13:41:31|
|960 forum posts|
3896 forum posts
I'd buy some but I can't afford the price of air-conditioning to keep my workshop at 20 degrees C year-round so they actually measure what they say they do.
|Douglas Johnston||14/12/2019 14:52:29|
657 forum posts
I bought an imperial set of used carbide ones off ebay a while back for about £100. Being carbide there was no rust but a few of them were slightly chipped. They appeared to have had quite a bit of use, but were from a very good UK maker with an original price of over a grand, and still in a condition to be very useful. For hobby work they do me fine and if I was doing it again I would love to inspect them before purchase, but that is seldom possible.
|Andrew Johnston||14/12/2019 15:30:03|
5081 forum posts
Just as well I'm not a muddle engineer then; at least not like Chuck.
I've got full sets of steel imperial and metric slip gauges, both bought on Ebay some years ago. Both have old calibration certificates. The sets are accurate to at least two orders of magnitude better than I need. So even if they're a bit worn or not exactly at the right temperature any errors are still less than I can measure.
I use them for sanity checking micrometers, setting up sine bars and for measuring slots, both when machining and to get a size when I need to machine a mating part. I do not use them as parallels or packing.
1342 forum posts
I bought a set some years ago from someone who had taken a college course and got stampeded into buying a lot of stuff that he didn't really need. He decided it wasn't for him and let his purchases go for a song.
The slip gauges were workshop grade (can't imagine anyone in a home workshop setting needing better) and essentially new. All but a very few were still wrapped.
Do I use them often? No. Would I be without them? No. When you need a slip gauge, you need a slip gauge.
|Philip Powell||14/12/2019 19:24:40|
|63 forum posts|
At work as well as a very decent set of steel metric slips we have an old and I believe fire damaged imperial set with a few missing slips. The metric set we're not allowed to take into the machine shop, but the imperial set are used for packing/parallels, vey useful indeed when you need a packing piece a certain height and a multitude of other uses (not the metric set though).
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