# Anyone made their own mill parallels and if so, what tolerance is ok?



## HMF

Have any of you guys made parallels for your milling machine?
If so, how did you do it, and what tolerances are acceptable for a home shop guy.

Thanks.


Nelson


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## Tom Griffin

Parallels, like any tool or fixture should be a factor of 10X better than the parts you expect to make with them. In other words if you want parts good to ±.003, them your parallels need to be held to ±.0003. If you aren't concerned about height and just want to use them to mill parts in your vise, all that matters is that both parallels are the same height and that can be accomplished by grinding both at the same time, or match grinding them. Because of these tolerances, a decent set of parallels requires the use of a surface grinder unless you want to get into hand lapping, which isn't a whole lot of fun. 

Tom


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## HMF

TLGriff said:


> Parallels, like any tool or fixture should be a factor of 10X better than the parts you expect to make with them. In other words if you want parts good to ±.003, them your parallels need to be held to ±.0003. If you aren't concerned about height and just want to use them to mill parts in your vise, all that matters is that both parallels are the same height and that can be accomplished by grinding both at the same time, or match grinding them. Because of these tolerances, a decent set of parallels requires the use of a surface grinder unless you want to get into hand lapping, which isn't a whole lot of fun.
> 
> Tom



So making them yourself by placing a rectangular bar into the milling vise and flycutting it, will not produce satisfactory results unless your milling setup can hold extremely tight tolerances. Not many of us have a surface grinder in our shops. I don't even have room for it.

Nelson


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## Tom Griffin

It depends on what you mean by satisfactory. If ±.010 is acceptable for the parts you are making then you can absolutely make them on the mill. But don't forget, commercial made parallels are also hardened to resist damage through use. If you make them yourself, on the mill, they will be soft and susceptible to dings which further detracts from accuracy. With inexpensive imported parallels readily available it doesn't really make a lot of sense to make them yourself, even if you had heat treat and grinding capability.

Tom


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## 4GSR

My first set of parallels were made of cold rolled flat bar.  When they started showing their age and wear and drill/mill dings, I made new one.

Also had several sizes of HSS i used for parallels, too!

Used them for many years before the import stuff started coming around.


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## brucer

I bought 2 sets of import parallels about 20years ago, I still have them and still use them about everyday, tolerances were within .0002

http://www.ebay.com/itm/1-8-STEEL-P...789?pt=LH_DefaultDomain_0&hash=item4cfeafc5c5

 also get yourself 2 or 3 pair of 1-2-3 blocks..


 you might also want to get a set of 1/4" thick parallels they are pretty versatile also..


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## Splat

I thought about making my own, too, but went with a cheap Asian 1/8" set. I picked up this 1/8" set of parallels, model TPS-081, at Penn Tool in Maplewood, NJ, that seem to be a good set for the price. Victor/VME in Brooklyn has a 1/8" set, PP-18, for around the same price.


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## chief

Does This Count:lmao: Wind mill
I started working on this a few weeks ago and got it done and up on 14 April 2012The 41 inch rings are old steel wagon wheels,  the large blade turns one way 
and the small blade turns the other way, Everything is on Bearings 
I put it up where it is so the Wife can see It wile she is doing the dishes, 
And She Loves it,


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## boringbar

An older retire guy gave me a handfull of HSS cutting bits 3-4" long, 1/4" & 3/8" square several years ago. I've been using them as singles, pairs, stacked, and stacked pairs. The tolerances on them seemed very good and for setup on a milling machine they perform quite well, at least on my small home miller. I've never checked for price, I wonder how they compare with purchasing "parallels"?


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## Charley Davidson

If you don't have any then anything is better than nothing, Make you a set or two out of whatever material you have laying around. Since their main job is holding stuff up higher in the vice just make sure they are same height & parallel. If they get a ding just mill a few thou off till the dings gone.  But as stated before the imports are cheap and work great.


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## jocat54

boringbar said:


> An older retire guy gave me a handfull of HSS cutting bits 3-4" long, 1/4" & 3/8" square several years ago. I've been using them as singles, pairs, stacked, and stacked pairs. The tolerances on them seemed very good and for setup on a milling machine they perform quite well, at least on my small home miller. I've never checked for price, I wonder how they compare with purchasing "parallels"?




That is what I use most of the time--seem to work for me.


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## DMS

A set of soft jaws may fit your needs. These are vice jaws that fit in place of the stock (hardened) jaws. Typicaly made from mild steel or aluminum, you can bolt them on and machine them in place. As long as you don't remove them, tolerances are very good. You can also mill a small ledge near the top which serves the same purpose as a set of parallels. I have been using a set made from aluminum for a couple weeks and really like them.


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## Pontiac Freak

I wanted to learn how to use my fly cutter and other tooling so I made my own.  Started with 1/2" plate and cut to size.  Surfaced them together and then heat treated them.  Took them to work and learned how to use the surface grinder and made them matching on all sides   Could have bought them cheap, but I learned a lot making them so it was worthwhile for me.


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## easymike29

Pontiac Freak said:


> I wanted to learn how to use my fly cutter and other tooling so I made my own.  Started with 1/2" plate and cut to size.  Surfaced them together and then heat treated them.  Took them to work and learned how to use the surface grinder and made them matching on all sides   Could have bought them cheap, but I learned a lot making them so it was worthwhile for me.



Pontiac Freak

Let me congratulate you for your effort. Too often the prevailing wisdom is "I can buy cheaper than making" As you have demonstrated, there is a lot to learn about machining whether a hobbyist or working in a shop. I would encourage you to also make sine bars/plates, Vee blocks, toolmakers vise, and even a radius dresser if you do much surface grinding.

When I was still in the working world my apprentices had to make a set of four 1-2-3 blocks, all flat, parallel and square in all directions within .0001" T.I.R. before they could be trusted with any of the tooling we fabricated. The .0001" T.I.R. had to be demonstrable with a dial test indicator, not a cylindrical or other type of light source method.

Gene


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## Frank Ford

Indeed, it does depend on what tolerances you need.  I do LOTS of "casual" work, so I made up some disposable parallels that I can drill or mill into without worry.  In fact, one of my most used parallel sets is made of wood - for use on the drill press, thus:




I also made up a big batch of aluminum ones for the mill:




I can also use them for filtering by milling or drill features into them for specific work holding.

For more serious work, I bought the usual sets of 1/8, 1/4, 1/2 inch thick ground steel parallels.


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## Mid Day Machining

When I need special parallels, I make them out of 1/8 or 3/16 inch thick 7075 aluminum. Then when they get beat up, I'll cut them down to a clean up and keep using them. As long as you make your parallels straight and the same size, who cares what you make them out of as long as they work for you.


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