gage block set rec

[petertha]

I'm looking at getting a sine vise for angle setting in the mill & therefore gage blocks to set up. Just happened to be looking at Fowler as reasonable shop-grade cost option. There isn't an appreciable price difference between a 36 & 81 block set.

I've read up on the basics of making up stacks to achieve resultant angles. But without doing the math against the available thickness permutations is there a rule-o-thumb like a 36-set get you to within a (negligible to me) 1/4 degree or so? Usually I would just say bigger is better. OTOH, if I don't need a suitcase of specialized sizes then maybe 36 is fine?. Any other reasons a person would regret buying 36 over an 81?

direct link if my screen grab isn't clear
http://jwdonchin.com/Fowler/Catalog/FowGageBlocksSetMaster.pdf

 

[purpleknif]

If you're not in a hurry you can find "economy" grade 81 pc sets for around $80. That's what I got and would definitely recommend .

 

[Blogwitch]

Unless you are after super accuracy, then you could consider what I have been using for the last few years.

http://littlemachineshop.com/products/product_view.php?ProductID=1757

John

 

[kvom]

A shop grade set works fine for me. I've used the blocks more for setups on surface plate than for setting a sine plate. I have a set of angle bars that are good for integer degrees and that works for be 99.9% of the time. I bought a 81 piece rectangular set from Enco a long time back on sales for less than $100.

 

[petertha]

Unless you are after super accuracy, then you could consider what I have been using for the last few years.

http://littlemachineshop.com/products/product_view.php?ProductID=1757

John

For my purposes I think the shop grade are perfectly fine. Probably better than tolerances of vise, setup, cutting accuracy etc. so what the point.

But the LMS set shown brings up other question. Is there advantage to circular discs vs. rectangular blocks? I don't quite understand the concept - are they center threaded vs. the wring-together concept or something?

 

[GailInNM]

I second what John (Blogwitch) says. I have a similar set that I have been using for about 30 years. it serves my needs quite well and with a 3 inch sine bar it will give you an accuracy of about 0.02°. Better than that if you're using a 5 inch sine bar or vice. And, certainly better than my run of the mill machining.

A set like this is available from Enco also with a web price of about $50. If you apply one of their current promotions you can get a set for less than $40.The current promotion that I have a card on is for 20% off and free shipping. If you need the promotion codes I will send them to you.

I like the circular ones and use them a lot for setups. They screw together with the included set screws. Screws in my set are threaded 1/4-28 but I don't know what is being used now. With a screw together set you can make up a semi-permanent stack and use them wherever you need a precision spacer. As an example, I do a lot of small parts and with a locator on one and my mill vice I make a spacer up the same dimension as part to put on the other end of the mill vice to ensure parallel clamping.

Gail in NM

 

[rodw]

Might cost a bit more but I bought an 87 piece metric set from here
http://www.ctctools.biz/gauge-blocks/

Very impressed with the quality, the box is the best of any of my tools.
They only do 2" sine bar which is nice to set the compound angle against the tailstock but a 4" one would be nicer as it would be more accurate..

 

[petertha]

Thanks all. Another question re the sine vise itself. Generically, most seem to look like this. The gage block stack goes under the rear dowel pin to elevate & side straps secure position.

But what is the typical mill setup? I can accommodate this base size in my larger mill vise, but kind of appears only holding ~2/3 end (orange arrow), kind of cantilevered, as opposed to gripping the whole base because of the side arms? Doesn't seem like toe clamping directly to mill table is the right way to go? I'm guessing maybe these are more intended to stick down to mag plates or something? Are there different styles or what am I missing?

 

[petertha]

Or... maybe its ok to direct mount to table?

http://www.practicalmachinist.com/vb/general/finding-z-height-sine-vise-286555/

 

[rodw]

I may be way off the mark, but I thought you treated them like parallels. Set the angle, tighten the vice and then remove the sine Bar. I hadn't considered buying a vice like that.

 

[rklopp]

A 36-piece set will handle most of the lengths an 81-piece set can do. It just requires more blocks in the stack to get there. If you wring correctly, it should make no discernible difference to anything you can do in a home shop.

 

[GailInNM]

Because of their construction sine vices are not very rigid. They are not suitable for more than very light cuts when milling. More often they are used for inspection and on a surface grinder for finishing cuts were the cutting loads are very low. because of this it really won't make much difference how you mount the vice for milling as the vice will be more flexible than the way you mount it.

For milling it is better to set up a sine bar in your regular milling vice and either mill with the part located on the sine bar or mounted in a small screw less vice sitting on the sine bar and clamped in the regular vice.

Home made sine bars are easy to build to suit your vice and will easily give accuracies of better than one tenth of a degree. I had a thread on making shop built sine bars a long time ago but can't find it now. I did find the photos that went with the thread. They are pretty much self-explanatory but if you want more information I can give you some.
Gail in NM

 

[Wizard69]

I'm looking at getting a sine vise for angle setting in the mill & therefore gage blocks to set up. Just happened to be looking at Fowler as reasonable shop-grade cost option. There isn't an appreciable price difference between a 36 & 81 block set.

If the price difference doesn't bother you go for the larger set.

I've read up on the basics of making up stacks to achieve resultant angles. But without doing the math against the available thickness permutations is there a rule-o-thumb like a 36-set get you to within a (negligible to me) 1/4 degree or so? Usually I would just say bigger is better. OTOH, if I don't need a suitcase of specialized sizes then maybe 36 is fine?. Any other reasons a person would regret buying 36 over an 81?

A 1/4 degree is a lot. What size set you need depends upon how flexible you want to be. For a hobbiest you don't commonly need to hit every fractional position between 0° & 90°.

One thing to consider anyways is making your own spacer if you find yourself using a specified angle often that isn't covered by one block in the set. This makes set up far easier.

Not to dismiss the importance of a good sine bar but a lot of setup grief can be addressed by the use of angle references, squares if you will. These are often had in sets of six or so and cover the common angles you may need to address in a set up.

direct link if my screen grab isn't clear

 

[petertha]

Because of their construction sine vices are not very rigid. They are not suitable for more than very light cuts when milling....For milling it is better to set up a sine bar in your regular milling vice and either mill with the part located on the sine bar or mounted in a small screw less vice sitting on the sine bar and clamped in the regular vice.

Thanks for this advice, exactly what I was concerned about. Actually to back up one step, a sine bar was actually my first inclination before the sine vise. My mill vise is a 5" jaw width, so I'm hoping that a common 5" (center-to-center distance of sine bar dowels) can be accommodated on the mill vise horizontal flats. ie one dowel rests on a flat & the gage block stack maybe traverses a bit. That's the concern. Maybe these 5 sine bars are kind of oriented to be used with nominal 6" vises?

On the shorter side I found one 2.5" center-center. But that's maybe getting on the small side, actually need to check, might fall inside the mill flats. I appreciate the 'make your own' rec, it might come down to that. I'll keep checking, maybe I can find a oddball metric size or something.
Hindsight: yet another thing when considering a mill vise.

http://www.kbctools.ca/products/MEASURING @@26 INSPECTION/BLOCKS/SINE BARS/6071.aspx

 

[petertha]

A 1/4 degree is a lot. What size set you need depends upon how flexible you want to be. For a hobbiest you don't commonly need to hit every fractional position between 0° & 90°.

I just threw that 1/4 deg number out, I have no idea if that's within the difference range of the blocks & guessing its a function of the sine bar center-center-distance. What I was more trying to say is even a setup to x.xxx degrees accuracy is probably going to translate into something different in my own machining, drift of a drill bit, minor slip during milling, surface finish etc.

One thing to consider anyways is making your own spacer if you find yourself using a specified angle often that isn't covered by one block in the set.

good tip.

a lot of setup grief can be addressed by the use of angle references, squares if you will.

That's what I've used thus far.. well kinda. I have a offshore graduated set with back notches (maybe what you are loosely calling square). It worked reasonably well, but the jig I'm making is 2" wide &the angle is about 3/16". There was a teeny amount of drift across the flat of my part because I supported the angle wedge adjacent to one mill jaw. So its kind of like milling a part with only one parallel under instead of adjacent to 2 jaws. A picture will make this clearer, but anyway I've since found a cheapo set that are nominally wider, ~ 1". For even/nominal angles or similar stacks, these are easy & quick to set up.