Interesting project, and if i may i shall add a few hints when "chasing tenths ". First, surface finish is vital, you can measure and it maybe perfectly in spec but if the surface is not dead smooth the first time you slide a bearing on the part will end up undersize due to the rough peaks getting compressed. Second, as you found push off is a problem, not only in the part bending (as RobRenz correctly says everything is made of rubber) but aldo the oil film on the cross slide leadscrew. The heavier the cut the more the oilfilm is compressed but on light, ie finishing, the weight of the cross slide is enough to stop it moving away. The answer is to preload the cross slide on finishing cuts to match the load of a heavy cut, this can be achieved by pulling the tool post away from the work for the last few cuts. In addition the use of a really sharp correctly shaped and honed tool will allow proper precision and possibly the use of a roller burnisher to improve the surface. The above may be overkill for general use but if you are chasing tenths or microns worth bearing in mind. I hope I'm not preaching to the converted. 😆
Chris that is fantastic advice and I thank you for sharing your expertise. I certainly learned a lot during this project. Achieving precise measurements takes preparation and measured approach. 👍🏼👍🏼. Gilles
@@LetsRogerThat you flatter me, but my philosophy is if you know something and don't pass it on it is lost when to are pushing up the daisies. If you haven't come across roller burnishing I have a simple beginners video showing the technique on my channel. Chris
Great video. Glad you decided to address the shaft/bearing issue. There are 10 ways to skin that cat. You can’t go wrong going with a New shaft. Learning about interference fits a New tool added to your tool belt. Have a great day!
We have reworked and repaired many spindles over the years. A good tip to save re making the whole unit is to (I work in the cylindrical grinding department) grind the O.D. Diameters undersize approximately .003”. Being either the bearing diameter or the seal mating surface. Then have that area chrome plated at least .006” thick. Then grind to proper spec. The chrome will be stronger than the hardened steel so the spindle now will last longer than the original.
6205 bearings? haha! these are deep groove bearings, and you don't use deep groove bearings on a spindle, they have a very big radial clearance so the spindle is going to wobble like a pen in hand when you move it. The only way you can use deep groove bearings on a spindle (yeah, because they are cheap!) is if you cut it in half (or like 2 thirds) so you can make an angular bearings out of two deep groove bearings and when you preload the resulting thing the radial clearance is going to disappear. The balls of deep groove bearings from japanese manufacturers are nanometer-scale precise so you would get a precision spindle the cheapest possible way. And this is what I was about to do before I discovered the tapered rolling bearings and because I don't need to run my spindles at high RPM, tapered bearings are just the same as good as P3/P2 class angular contact bearings which sell at 500 bucks per set (or more expensive). I have measured the tapered roller bearings and they give a half a micron precision, pretty good for a self made lathe so .... no need for angular contact. Tapered bearings also better than angular contact because they won't wear out as bearings made with balls would. TLDR: I recommend anyone who is doing their own spindles to download the SKF manual on super-precision bearings, it is a must-read 424 page document for any spindle designer, you will understand everything about precision brearings and will know what kind of bearings should you use (either 70XX series or for example 718XX series), also this manual contains drawings for lots of spindles and tells you which bearings should you use and how should you place different types of bearings for lathe, milling machine, high load lathe, and so on ... very good read.
@@LetsRogerThat I’m sure I’ve thought about filming out in the shop but my shops a cluttered mess and I’d have to get it organized before it’s even worth trying to film anything in there
You released this 8 months ago. Did the previous owner of the surface grinder discard a part of the spindle? Seems there should be a spacer between the two bearings (inner race as the outer race appears to be the preload adjustment) to preload the balls, forcing a angular contact and keeps the spindle from moving axially. Did I miss this in the video?
The previous owner I presume, might have replaced the original spindle with a homemade spindle. The spindle did not match the manufacturer diagrams. So you didn’t miss anything. But that’s ok, the grinder now works very well and as a hobbyist I’m pleased with the results.
@@LetsRogerThat I purchased one of those Cheap surface grinders that are known as MJ7115 models. I got mine from Harbor Freight mail order in 1991. I was in the spindle last year as there was always some surface finish issues. They used cheap deep groove ball bearings as the front bearings that supported the grinding wheel, it was a solid arbor that the motor drove directly, as the motor is in the same housing as the spindle. I found some angular contact ABEC7 bearings on eBay, a bit pricey to fix a junk machine. Better surface finish, but still not what I want. Some of that is the balance of the wheels. I found the single wheels I was getting off eBay to be discards as they had inherent out of balance issues as the vitrified abrasive had density issues. Bad enough that they can't be balanced. At least the machine used a standard wheel hub. Just this past week, I spent time sharpening endmills, lesson, they are not worth the time in front of the machine. In my case the ends were damaged to where I had to cut the end off and start over. The time it takes to grind the secondary relief is way beyond the value of the mill, and as I've collected so many, I have several life time supplies to use up. Your experience would have been good to see last year.......
Interesting project, and if i may i shall add a few hints when "chasing tenths ".
First, surface finish is vital, you can measure and it maybe perfectly in spec but if the surface is not dead smooth the first time you slide a bearing on the part will end up undersize due to the rough peaks getting compressed.
Second, as you found push off is a problem, not only in the part bending (as RobRenz correctly says everything is made of rubber) but aldo the oil film on the cross slide leadscrew. The heavier the cut the more the oilfilm is compressed but on light, ie finishing, the weight of the cross slide is enough to stop it moving away. The answer is to preload the cross slide on finishing cuts to match the load of a heavy cut, this can be achieved by pulling the tool post away from the work for the last few cuts. In addition the use of a really sharp correctly shaped and honed tool will allow proper precision and possibly the use of a roller burnisher to improve the surface.
The above may be overkill for general use but if you are chasing tenths or microns worth bearing in mind.
I hope I'm not preaching to the converted. 😆
Chris that is fantastic advice and I thank you for sharing your expertise. I certainly learned a lot during this project. Achieving precise measurements takes preparation and measured approach. 👍🏼👍🏼. Gilles
@@LetsRogerThat you flatter me, but my philosophy is if you know something and don't pass it on it is lost when to are pushing up the daisies.
If you haven't come across roller burnishing I have a simple beginners video showing the technique on my channel.
Chris
@@chrisstephens6673 I ascribe to your philosophy Chis. I will definitely watch your videos. Thank you. Gilles
@@LetsRogerThat I must record some more, but I only video when I have something to share rather than keep doing one a week, but with nothing to say .
Ta, I have learnt something.
Great video. Glad you decided to address the shaft/bearing issue. There are 10 ways to skin that cat. You can’t go wrong going with a New shaft. Learning about interference fits a New tool added to your tool belt. Have a great day!
Thank you. That will indeed come in handy in the future. :) Gilles
We have reworked and repaired many spindles over the years. A good tip to save re making the whole unit is to (I work in the cylindrical grinding department) grind the O.D. Diameters undersize approximately .003”. Being either the bearing diameter or the seal mating surface. Then have that area chrome plated at least .006” thick. Then grind to proper spec. The chrome will be stronger than the hardened steel so the spindle now will last longer than the original.
Fantastic advice. Thank you Kevin.
6205 bearings? haha! these are deep groove bearings, and you don't use deep groove bearings on a spindle, they have a very big radial clearance so the spindle is going to wobble like a pen in hand when you move it. The only way you can use deep groove bearings on a spindle (yeah, because they are cheap!) is if you cut it in half (or like 2 thirds) so you can make an angular bearings out of two deep groove bearings and when you preload the resulting thing the radial clearance is going to disappear. The balls of deep groove bearings from japanese manufacturers are nanometer-scale precise so you would get a precision spindle the cheapest possible way. And this is what I was about to do before I discovered the tapered rolling bearings and because I don't need to run my spindles at high RPM, tapered bearings are just the same as good as P3/P2 class angular contact bearings which sell at 500 bucks per set (or more expensive). I have measured the tapered roller bearings and they give a half a micron precision, pretty good for a self made lathe so .... no need for angular contact. Tapered bearings also better than angular contact because they won't wear out as bearings made with balls would.
TLDR: I recommend anyone who is doing their own spindles to download the SKF manual on super-precision bearings, it is a must-read 424 page document for any spindle designer, you will understand everything about precision brearings and will know what kind of bearings should you use (either 70XX series or for example 718XX series), also this manual contains drawings for lots of spindles and tells you which bearings should you use and how should you place different types of bearings for lathe, milling machine, high load lathe, and so on ... very good read.
Thank you. Great tip. I did read the manual butI appreciate the advice.
Nice little series I seen ya posted gonna watch this thing love when someone post the hole Shabang in one day
Thanks Jeremy. I kinda like that too. But editing 150 videos was lets say, interesting lol. Gilles
@@LetsRogerThat I’m sure I’ve thought about filming out in the shop but my shops a cluttered mess and I’d have to get it organized before it’s even worth trying to film anything in there
@@jeremycable51 Its a constant struggle here too ;)
Which material use sir
Pre hardened 4140
You released this 8 months ago. Did the previous owner of the surface grinder discard a part of the spindle? Seems there should be a spacer between the two bearings (inner race as the outer race appears to be the preload adjustment) to preload the balls, forcing a angular contact and keeps the spindle from moving axially. Did I miss this in the video?
It would be a thin ring between the two inner races, if it had one.
The previous owner I presume, might have replaced the original spindle with a homemade spindle. The spindle did not match the manufacturer diagrams. So you didn’t miss anything. But that’s ok, the grinder now works very well and as a hobbyist I’m pleased with the results.
@@LetsRogerThat I purchased one of those Cheap surface grinders that are known as MJ7115 models. I got mine from Harbor Freight mail order in 1991. I was in the spindle last year as there was always some surface finish issues. They used cheap deep groove ball bearings as the front bearings that supported the grinding wheel, it was a solid arbor that the motor drove directly, as the motor is in the same housing as the spindle. I found some angular contact ABEC7 bearings on eBay, a bit pricey to fix a junk machine. Better surface finish, but still not what I want. Some of that is the balance of the wheels. I found the single wheels I was getting off eBay to be discards as they had inherent out of balance issues as the vitrified abrasive had density issues. Bad enough that they can't be balanced. At least the machine used a standard wheel hub.
Just this past week, I spent time sharpening endmills, lesson, they are not worth the time in front of the machine. In my case the ends were damaged to where I had to cut the end off and start over. The time it takes to grind the secondary relief is way beyond the value of the mill, and as I've collected so many, I have several life time supplies to use up.
Your experience would have been good to see last year.......
@@f.hababorbitz for what it’s worth you can always call on me and I’ll help you as much as I can. Gilles
Nice!
Thank you
Sir blohm 75spindal repairing vidio