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steel parallels

Charlymich

Plastic
Joined
Jul 30, 2018
Brand new to forum. Using a brand new Magnalock 16 X 32 electomagnetic Chuck. Separators run front to back. It is replacing a Chuck the same size, but separators on old one ran side to side. On the old chuck, I used steel parralell blocks along the rear of table to keep parts in sraight rows. I grind hard metal alloys that don't always stick down very good. Will have 30 to 50 parts on table at times. Here's my problem. On the new chuck I put the 2 steel parralell blocks (approx. 1" thick X 2" hi X 15" long) accross the back it causes a tremendous magnetic drop on my first row of parts. If I turn chuck off and remove blocks, the force increases (with chuck turned back on). This did not happen on previous chuck. Can this be installation error, or is there some properties of the magnetic fields that I don't understand causing this. Any help appreciated.
 
Once had a job that did not want to hold for a full chuck of many parts. I ground my part seporators to be near part finish height and Put a little side taper going smaller at the down-side (on the chuck)using gun blue to identify the top (larger width side). Small out of square of parts can reduce hold or make parts to want to fill the empty space to the block-ins..the small taper sides corrects this problem.
Guess you may have to get more off the back rail to find the better place for first row. Mild or mild hardened spacers and parallels carry the mag hold higher up on the part, better than very hard.
Wheel choice can be a factor in hold as to fine or to hard can stress the part hold.
 
The parts I used to recognize this problem are about 4" tall 2" W 3"W in oval shape, with 1" bore in center. I can Gage magnetic pull by tipping part. I checked with full load and single part. Could you clarify the properties of hard parallels. I believe I have very hard parallels, so you're saying the mag hold would be lower into the part, Causing a weaker hold?
 
Hard parallels do not carry the mag hold higher on the part as well as soft or mild hard. Block-ins should be near 4" tall if a long run job worth making block-ins. at least a bit over half the part height (near full height best). The bump should be at block-in height even if you must grind a side taper to the bump (place it hits the part.)
Solid back rail parallel good, with individual bump-ins (touching the front side also toiching high on the part best as high as the (back) bump rail parallel)

How much take is required? what is the surface finish need. If possible a larger grit wheel and a down feed to + .003 (or so)with down and long travel only.and then a quick dress to step across (cross feed) for a .003 take to finish.

Off chuck diamond set at .oo3 higher than the finish part size..so you know that .003 more will make size..look at dial or with set zero dial you make finish size with not checking. easy to hold .0005 this way (I have held .0002
with avery good machine and runing wet on a good day)...yes over a very long run the diamond will wear. turn the diamond to a new facet perhaps at 20 hours use.

with square sided block-ins on the go side just one slightly out of square part(on the go side or other side can make the set-up poor to lose the load or cause chatter.
Low block-ins are "trip overs" not block-ins.

Thread title sholld have been "Holding multiple parts in a Mag chuck" That so one might search the subject.
but with only two posts an expected error.
 
Thanks for good info. Due to finish requirements, limited part surface contact with chuck and metal types I rarely go beyond .001" down feed. I guess the root question should be: why did I not have this problem with my old chuck? The difference between chucks is pole direction. If that's what's causing it, then I'll modify behavior. If it's defective equipment or installatio, I'll fix it..
 
Can you rotate parts 90 degrees on the new chuck? That will let you know if the parts need to aligned with pole direction of chuck or if the new chuck is just crap. You dont even need to run them to see if they hold better.
 
I take total grindstock .020 - ,050 depending on part. Timed parts so different grindstock off each end. If I have half table with 24 pieces. It would be about 12 min per part. But it's not cut and flip. I have to time them
 
is it possible your new mag has less available hold down and too much is going into the parallels? can you relieve the parallels so they have less surface contact but still sufficient so they don't slide?
 
Your thought seems to be headed in the right direction. I'm not as knowledgeable as I should be of electromagnetic properties. Overall though, I have about 25% more strength than old chuck with table loaded or with 1 part. Except for the row along paralell
 
I use blocks along back primarily for keeping parts in line or parallel to chuck. There are times when I use large blocks in rear for very tall parts. My expectations are for this Chuck to accommodate these purposes. I will continue the slow process of getting More info from chuck manufacturer. P.S. rear rail supplied with chuck is insufficient as overhang of parts is too much off rear of table. I grind multiple diameter parts (usually on separate loads) so holes aren't an issue
 
I tried to keep a number of different widths of back rail parallels to change the set place running parts to try to use the full chuck at times and used a big oil hone to true up so not needing grinding the chuck as often. You might try a piece of CRS for back side parallel. Might just have a poor hold area because of the design of the chuck.

Had one job grinding long flat form cutters. Would fill the chuck length and grind five with one for the spotter. and needed to grind the chuck very often. I was the new guy and did not think of moving about the chuck..Now if I did/had that same work I would need skim the chuck way less often. Good old days.. perhaps 12 hours cranking a no auto feed 618 manual Reid.
 
Just 6 years in myself. I use multiple rail parralells from 1/4" - 2" but per application. Just learned recently from these posts about moving around on chuck. Didn't suffer much though because I use most of the chuck most of the time with various parts. Sometimes I would have to block them out 4" just to avoid pole intersects on my old chuck.
 
Just tried moving parralells 7"away from rear of table. No problems, no mag loss. Now convinced that it's the table or wiring or volt/wattage problems. I Think it's going to be a supplier's fix.
 
I'm operator in machine shop. New chuck is has about 25% more holding power. So if fixed will be slight improvement. If not fixed I am More comfortable running with less hold but consistent. They payed 15,000 for chuck and controller sight unseen (definitely not my decision). They promised 75% improvement. They bought 2. My job I guess is to make bad decisions turn into good ones. I'm hoping to find the problem, fix it and settle for better. Unless you know someone looking to buy a couple of chucks
 








 
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