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Royal Master 12x4 Help with thrufeed Taper

Timmahhh

Plastic
Joined
Aug 31, 2021
Hello everyone, first post. I have just taken over for my predecessor and am trying to help out for a situation that is currently word of mouth. I have not been present for a setup as of yet but anticipate one soon, so I am trying to gather as much info as possible to aid when the time comes. I have 4 Royal master 12*4 machines that are no longer able to hold a straight grind in thru feeding. We are seeing a -.0005 bowl taper in the middle of parts consistently (I.E. both ends are high, and the middle along the length is lower by about .0005). We have tried the adjustments to the regulating wheel dress path angles as described in the Royal Master manual, and in the previous history have had no issues with the straightness of pcs. This seems to be a new development over the past year that multiple different operators have experienced across all our machines. My operators have ensured that the guides were correctly set, as this was my first question. They also tried numerous different angles for helix and dress from close to 0 up to 5 degrees (matching them to each other as per royal master manual, nothing below the 0 line) of our machines have a belt drive system and 2 are motor driven for the regulating wheel. I wouldn’t expect the 2 to behave the same in regards to the taper if it was the drive system but both systems show the same taper. has anyone had this issue an could offer some insight on avenues that I can look for that may be the culprit of our bowl cut pcs?( I.E. both ends are high and the middle along the length is lower by about .0005). Thanks for your time, I look forward to reading the posts that come along.

There is a picture attachment from the manual to illustrate the taper but its hard to see it---->Barrel Taper.jpg
 
If you can give me the specs on your setup and I will try and help you out. I need to know the wheel diameters both grinding and reg. The part diameter and the thru feed angle that you guys like to run.

Donovan Horton
 
I'm thinking that the diamond setover could be the problem. Give us ALL information. A centerless has so many adjustments that incomplete info is useless.
 
I don't think the OP is coming back. He must have figured it out. But would you want to help me out. I made a program for setting up my centerless machines and I would like to see if you could give me some numbers that you use on your machine and see if I can predict the correct info for you. I need one of your best setups that you know works and works well. I need the OD wheel size, the Reg wheel size, the part size and height above centerline and your thrufeed angle? I will get rest of the info back to you.
 
Yeah and the OP probably has realized that his entire post was wrong. It was not cutting a taper, it was a barrel shape. Commonly caused by failure to dress the wheels, ( yes, both of them) when needed.
 
Hello everyone, sorry about the delay in returning. The "taper" in the title is not the correct term at all, I did include a photo from the royal master book to show the barrel in the post but the title is wrong. Just let me know so I can take note an become a better grind machinist. I am trying to learn as much as I can to help out everyone in a word of mouth situation. We will soon get a setup for this so I will get a chance to see what is occurring but it has not happened yet. We are currently using them but not in a thru feed capacity. Our Reg wheels are 6" diameter, our grind wheels are 12" diameter, historically for thru feed our helix angle is 2 lines to the right and the Dimond step over is 3 lines to the right. Thanks to all for your patience, I look forward to reading your replies and any information that I can.
 
Hello everyone, sorry about the delay in returning. The "taper" in the title is not the correct term at all, I did include a photo from the royal master book to show the barrel in the post but the title is wrong. Just let me know so I can take note an become a better grind machinist. I am trying to learn as much as I can to help out everyone in a word of mouth situation. We will soon get a setup for this so I will get a chance to see what is occurring but it has not happened yet. We are currently using them but not in a thru feed capacity. Our Reg wheels are 6" diameter, our grind wheels are 12" diameter, historically for thru feed our helix angle is 2 lines to the right and the Dimond step over is 3 lines to the right. Thanks to all for your patience, I look forward to reading your replies and any information that I can.

What is the part size?
 
This is how I would set it up.

The part will be .127" above centerline.
The Regulating wheel Dresser will be set to 2 degrees
The Helix will be set to 2.016 degrees. You need a little more angle in the Helix than the Dress but just a little. Use a indicator and trig it out if you need to. You might be able to run right at 2 degrees but I would put a little in it.
The diamond set over should be .125". The diamond should be moved towards the Grinding wheel in the positive direction of .125"
Try this out.
 
If part will not stay down between the wheels go down on the centerline.
Use .045 above centerline and .044 on the diamond set over. Use the same angles from above.
 
Per the Royal Master manual the work centerline should be 1/4 to 1/2 of the part diameter above the wheel centerlines. It says for the hourglass shaped part to check guide alignment. If aligned and still hourglass move both toward the regulating wheel.
I have always used 1/2 part diameter for centerline.
 
I never use that formula. I use a floating Gamma angle anywhere between 3.5 to 4.0 degrees. I use a constant diamond set over because I don't want to move the set over for every different part. I might run five different size in one day.
 
Thanks for the input! Donovan Can you clarify for me biased off my setup as described below.
Originally Posted by Donovan
The diamond set over should be .125". The diamond should be moved towards the Grinding wheel in the positive direction of .125"

Our Regulating wheel diamond step over scale is in 1/32" increments, so the .125 step over would be 4 hash marks. We have gone to 3 but not 4, also historically I'm told we are on the right hand side of 0 (away from the grinding wheel not towards it). To clarify I should bring my reg wheel diamond step over to the left past 0 by 4 hash marks towards the grinding wheel? I'm totally game; just wanted to verify as I am told we have lived on the complete opposite side.

Originally Posted by tdmidget
Per the Royal Master manual the work centerline should be 1/4 to 1/2 of the part diameter above the wheel centerlines. It says for the hourglass shaped part to check guide alignment. If aligned and still hourglass move both toward the regulating wheel.
I have always used 1/2 part diameter for centerline.


tdmidget; We have always used the formula in per Royal Master in our manual "1/4 - 1/3 the diameter plus .500= center height" off the casting next to the work rest blade to find for center height then shim blade accordingly. not the full 1/2 of part diameter. Again I'm game for trying it all on the path thru troubleshooting so we will try the different center heights. Also, the part diameter values you guys provided are off the work rest blade? or should i follow normal procedure and add the .500 to the partial diameter value and measure off the casting to set the rest as always?
 
In the picture below you will see a circle on the left and that is the grinding wheel 12" the right is the reg wheel at 6". The middle circle is a part the is 1.5" diameter. It is easier to see this with the big part. I have the centerline of the part to be ground at .375 above centerline of the grinding wheel and the reg wheel. You can see that the part does not touch the reg wheel at .375 but rather at .300 which is the tangent. This is what you want to set your dresser at. So for this part you would set the diamond set over at .300" up. Look to the far right of the reg wheel and you can see the triangle on top which would be your diamond. If you dressed it below you and can see it does not contact the part on the left hand side of the reg wheel but well below centerline. Now for the Royal Master they have there dresser mounted at a 90 degree which is on top. So now look at the drawing and you can see the diamond set over on the reg wheel. It needs to be moved to the grinding wheel.
 

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Here is a great picture of a reg. wheel the has a helix or angle in it. You can see it is not a straight cylinder. That is way the diamond set over is important.
 

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Awesome diagram an picture Donovan! It makes a ton of sense. I'm excited to try these things when we do our next thru feed setup and report back. Thanks for all your help Donovan an tdmidget.
 
Hi Donovan,

I run several RM 4 inch grinders and usually use experience to solve size and shape issues.

For me talking to RM has been hit and miss. Could you create a chart that indicates the proper adjustments to remove barrel shapes and hourglass shapes and tapers?

Most of us know how to adjust guides, but get overwhelmed with all the other choices.

Thank you,
Lost
.
 
The centerless grinder is the most frustrating machine that I know of. I is way harder to setup and run the CNC OD grinder or Lathes and Mills. Never done a CNC tool grinder. That is why I have no hair left. Anyways here is what I do.

Make sure at least your Regulating Wheel dresser and the Helix angle are the same to start with.

Run a part thru your machine and set the guides like you always would do. I like to get the parts to run about 3/4 to 7/8 of the way thru the machine. I use wooden sticks a lot and put pressure on the back of the part and see where the part stops grinding and then adjust. Longer pieces you and use a snap gauge and slide it up and down the part to see if there is a wave in it. What I mean is does the part size move up and down in size be a .0001 or .0002. If it does the part is probably going to far thru and you need to adjust.

If you get to this point and made the guide adjustments and you still have a hour glass shape then you adjust more angle into the Regulating wheel. Move it a little and rerun your part and see if it changes. It will I promise, and you my have to do that a couple of time to get the part running straight.

If the part is straight but the back end is going small and the guide are correct then you are going grinding to far thru the machine and you need to bring the reg wheel back to the front side and get it cutting 3/4 or so.

That is what I do. I use a calculator that sets my angles and height of the parts and reg wheel angle.
 
I never use that formula. I use a floating Gamma angle anywhere between 3.5 to 4.0 degrees. I use a constant diamond set over because I don't want to move the set over for every different part. I might run five different size in one day.

I should have never said that I never use that formula. I do use that when I have parts smaller than .125". (I actually forgot about that) The reason is my 20" wheel will get into the blade at the higher setting and I don't have a more narrow blade. So sorry about saying that. I did run a .095" part and used the .045 above centerline and .044 diamond setup. It worked like a champ and should work fine for you also.
 
Hey everyone, we finally have pcs to try this new info for our royal thru feed setup. We discovered that the formula that had been transcribed did indeed have us below centerline (that or where we are using as or constant for taking this measurement). After correcting that and moving the part above centerline by what we thought was the value we were looking for, the work rest blade was coming into contact under center line with the reg wheel. the work rest balde is the correct blade as per the royalmaster book (TFC-050). We even tried the next size down to see if that would clear and it came in contact at the same location on reg wheel and work rest blade arc. It would appear that there is clearance at the front of the machine, and in contact at the back. But with less helix, operator said there wasn't enough pull. From all the hardware that we have and the previous documentation I can get my hands on it seems as if they were running below centerline. We even looked thru an old notebook from multiple predecessors ago who had the same formula of 1/4-1/2 part dia+.500= Center Height. Currently we are stuck, I feel that there is something very obvious that I'm just not seeing, could even be as simple as where we are defining this measurement from. Current documented practice is by removing the front guide to use the work rest casting machined flat under the front guide. Thanks again.
 








 
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