Bearing Question

[Rich Riddle]

I am replacing the cutter head in a MiniMax FS35 with a Shelix head. Might as well replace the two bearings which are differing sizes. I have the appropriate Nachi bearing in the garage (I rebuilt lots of tools and keep extras). Question is should I replace the current bearings which are NSX bearings (made in England) with the DU suffix with Nachi bearing (ones I prefer) with the ZZE suffix or the 2NSE suffix? Thanks.

[Erik Loza]

Rich, is there an actual design difference between the NSX's ands the Nachi's? I use Nachi bearings, too (Honda guy, for the transmissions...) but do know that I could have three different Nachi bearings for the exact same application in my hands, each would have a different suffix, but they all could work fine. The coding is mysterious to me, too. LOL, I don't know if this is any kind of answer.

Erik Loza
Minimax USA

[Dave Cullen]

Either would work. The ZZE has metal shields which should make them tighter sealed against dust.

[Glenn Bird]

The ZZE suffix indicates dust shields both sides. The 2NSE suffix indicates contact seal both sides which is the tighter seal and should be similar to the DU suffix on the NSX bearing.

[Bill A Hagen]

Just because the external dimensions of the bearing match doesn't mean they are interchangeable. The type of grease in them might be different and the internal clearances between the races and the balls might not be the same. There are bearing made that have lots of internal clearances (used in situations where the bearing has a heavy pressure fit in a bore and/or on a shaft), this causes the races to change dimension and to take up some of the internal clearances. Generally I would think a standard clearance bearing would be fine in most cases, the exception would be in machinery that has high loads (air compressors would be one). Just something to keep in mind when replacing bearings, if you can contact the mfg and find out what is correct bearing size, clearance and grease. If a mfg makes enough equipment the cost difference to change any of these features in a bearing is very little cost.

[David Kumm]

When you get into the bearing world it gets complicated. Generally precision means how concentric the inner and outer rings are. ABEC 1 and P 0 are standard going up to ABEC 7 and P4- there are higher but irrelevant. Clearance is the distance between the balls and races. If it were me I'd put a P5 normal clearance standard pressed steel shielded bearing. Natchi , NSK, or NTN are pretty much the same. Not easy to find precision in a shielded or sealed so I wouldn't sweat it but probably would not use a C3 loose fit although the difference is pretty slight. . . You should think of the bearings as spindle bearings as an application rather than motor bearings that see more heat and need a looser fit. If you are running a machine hard for long periods you might want the looser clearance fit too but on a hobby basis I would stay standard. You do have to ask as some companies- like SKF JEM bearings are C3 as standard, most are a little tighter and are spec'd somewhere between C2 and C3. Shielded are usually spec'd for higher rpm than sealed. You can google bearing nomenaclature for all companies and get a real education. We haven't even talked about cage design and material but not really necessary for bearings running at < 5000 rpm. Dave

[jack forsberg]

all that bearing stuff don't mean a thing really. your changing the head so what you had don't mean a thing ether. helical heads has thrust loads on them so you looking for a bearing with better thrust load in the same size. What does the cutter head mader spec?

[Rich Riddle]

What does the cutter head maker specify?

Shelix, the cutter head manufacturer, doesn't specify any particular type of bearing, just to use bearings of the original size. The Shelix head is made to the exact specifications of the Mimimax original head where the bearings get placed, so the same size bearings will work.

[Chris Fournier]

Match the bearings spec that came out of your machine as close as possible, simple as that. Manufactured in the West or Japan preferrably. Change the seals from rubber to steel and you will have a real mess on your hands...

[Rich Riddle]

Dave,

Thanks for that information. After looking at the removed bearings, they had some "crud" around them even though they are well protected. According to the owner's manual, the Minimax jointer/planer head spins at 4800 rounds per minute (RPM) and that the 2NSE bearings can handle 6500 RPM. Shielded bearings handle higher RPM's but the sealed 2NSE bearings apparently keep out more contaminants. Thanks a lot for the information and the proper Google search term. That helped a lot. There's certainly a lot more information associated with bearings than meets the inexperienced eye.

[David Kumm]

Jack, where does the axial ( thrust load come from on a planer bearing. My 299 ITCH which was an original insert version uses all radial bearings as do all my shapers and straight knife machines. I've often wondered why a low angle angular contact bearings set in opposing directions aren't used but I've never seen them in any of my machines. Sealed are fine. A benefit if you find old stock is you can take off the seal and replace the grease or at least check it out. Shields get wrecked if I remove them. Dave

[jack forsberg]

Dave even the old Babbitt bearings planers had keys on the shaft (v shaped) so that it gave the head some thrust loading when a board was put through on an angle. With helical heads in ball bearing machines the bearing lock the head in place and provide radial and thrust load play clearance. the knifes in some of the true helical heads give thrust load to the bearing because the knife is angled.How much thrust i would guess that depended on the machine and depth of cut but it more than straight knifes. This is the real question and its not about what seals to use. Radial bearing provide good trust load and deep grove even better if loaded. deep grooved would be as good if not better than AC bearings. Being a horizontal spindle i see no need for AC bearing. I find most of the machine today use cheap easy to replace bearing so for the most part that where it does not really matter. I on the other hand like machine made better than they do today. so if your asking i say spend the extra $40 on good bearings if you put in a helical head. you have the money if you got it for the head.

[Rich Riddle]

Here are a couple of pictures of one bearing removed from the Minimax. You can see one is clearly very dirty and that's why I want the best bearings for dirt. If you folks have any other suggestions for better bearings, please offer your recommendations. The bearing sizes on this unit are 6205 and 6206 respectively.

Clean Side.jpgDirty Side.jpg

[David Kumm]

Yes, the deep groove bearings I see on machines- 6200 or 6300 series - are radial but do have some axial ratings too. I would guess plenty for the load they get on planers or shapers. I'm with you in that I err on better bearings but they are more difficult to source in the larger sizes old machines used. Sometimes it is easier to find them from suppliers in China. Same bearings made elsewhere but mailed from China. Go figure. Dave

[jack forsberg]

Yes, the deep groove bearings I see on machines- 6200 or 6300 series - are radial but do have some axial ratings too. I would guess plenty for the load they get on planers or shapers. I'm with you in that I err on better bearings but they are more difficult to source in the larger sizes old machines used. Sometimes it is easier to find them from suppliers in China. Same bearings made elsewhere but mailed from China. Go figure. Dave

Ya that was an interesting bearing story that Arthur had on the Timken bearings. though i like to see it happen twice

The 6200 are the cheap bearings i was talking about. these are $12 bearing. your going to change them every 10 to 15 years so it don't mater it makes no sense for the new maker to make a better spindle to out last the bearings. BTW this is the most common motor bearings out there so they will be around for while. get a C3 SKF 2RS. you really don't have provisions for better bearing that will make a real difference.