Should the sign plate be mounted to the machine or on a magnetic chuck?

Should the sine plate be mounted to the machine or on a magnetic chuck?

One of the first projects I want to do with the surface grinder makes a sin plate. I would like it to be big enough to hold the magentic chuck so I started wondering, why not just make the sin plate mountable to the table and mount the chuck to that. Instead of having two magnetic chucks.

People will have a better understanding of what you're asking if you use the word "sine" in your title...

Well, I thought I fixed it.

When editing it shows sine but when I view it it's still sigh.

There are magnetic sine chucks but they're expensive for the number of times you'll need them but if you have enough cash and/or need one that often then that's the simplest method. I've usually just set a non-mag sine plate with the appropriate grinding vise mounted to the sine plate. Part of that is my distrust of smaller mag-chucks and part is I don't like to purchase expensive things I won't use enough. More tooling on the mag-chucik also increases the work height and most surface grinders don't have much to begin with. Removing the grinders mag-chuck means re-grinding when you put it back on. You also need to keep in mind the expected level of accuracy for the work, shop tools often have had some abuse to the roll on the sine plate/chuck and you can see this as a flat spot on the contact surface. Using more than just the machine mag-chuck also adds potential error into the equation as nothing is perfect so if a couple of tenths error is going to affect the expected outcome then you have other issues to address. Making your own tooling is encouraged just be aware of the level of accuracy (after verifying it) the tooling can produce. No point in insisting on ultra precision tooling when +/- 1/2 a degree is within tolerance called for, uncalled for fussiness usually means the job takes longer to finish. Purchasing tooling still means it should be checked, especially if used. Making your own tooling takes more time but also reveals what it takes to make something flat, square, and parallel to an expected tolerance. Making your own sine plate is fine but distance between centers is critical to accuracy so adjust your construction or your expectations accordingly.

I have a 3 x 6 sine plate with 1/4 screw holes, and a 6 x 6 magnetic. I use the mag sine chuck on top of the regular chuck most of the time, rather than the hold down sine plate. But its not used very often.

Ah, so it's less common to make angle parts but more often then not you will be making square parts.

We just put the sine plate on the grinder when needed. You don't what the grit/ coolant getting into the hinge all day. It will rust over time.

When we remove the sine plate we oil it down.

Our sine plate has a magnet on it.

SirRage said:

Ah, so it's less common to make angle parts but more often then not you will be making square parts.

Click to expand...

-That will depend upon the type of work you do. For stamping die work it's mostly squares but it's not uncommon to have forms in the punch/die section that have an angular detail that can require a sine plate. There's also various geometry for pilots that can require a spin fixture on a sine plate. I purchased an older model of a spin fixture with a built-in sine plate for this but that's just my choice. Various slides and cams in stamping dies also benefit from using a sine plate/chuck as well. What you will encounter only you will know but the bulk of what I've done over 30 years has been square/parallel with about 5% angular details in an otherwise square/rectangular workpiece. It's all about your work and the methods you like to employ. It's also the level of precision needed. A sine bar/plate/chuck is used when an angle is critical, for general work a set of simple angle blocks/parallel is sufficient for a lot of work and far easier to make. A sine bar/plate/chuck is also used when checking/verifying or reverse engineering something so it doesn't always get used on the grinder, they can also be used for a set-up in the mill provided it's only subjected to minimal cutting forces. Your last question suggests that you haven't been machining for very long?

As far as referencing the wheelhead, the magnet will be the flattest, most parallel plane on the grinder, so it is ideal for the reference plane for other tooling.

If you properly set up the chuck with the rail edge parallel, and occasionally dress the rail, it will be the fastest, most accurate way to locate other accessories parallel/perpendicular.

I used to worry (posted Q's on here} that one of my large tilty or sine chucks would be de-magnetized by using them on an electromagnet. Also about the pull on the center of a long without a sine plate base.





No one really had a good answer, and I used to bolt the swivel chuck down to the top of the main electro-chuck. (this has its own potential error, since the magnet is only dressed flat when it is on, but close enough.

Later I quit worrying, and just put in on the magnet. Be really clean with everything.
I oil everything before putting it away (LPS#2). Every now and then i get really disgusted with the build up grime, and wash it in the slop sink with Zep or similar lye base. Rinse it with really hot water. Towel off, most of the water will evaaporate. then dunk in alcohol being sure it submerges the hinge & roll parts. Then let that evaporate, and spray again (yuck) with the LPS. If I don't go through this process it will rust in my shop, or get terminally groty.



smt