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R8 Drill Chuck Arbors

AdamC

Cast Iron
Joined
Jun 16, 2011
Location
SE PA
I'd like a couple new R8 arbors for my drill chucks. I have a few smaller chucks with 1/2" shanks, but I'd like a few with R8s.

I see new Chinese made arbors for $20, and Jacobs for $120 that are made in China. Then there are middle of the road arbors, made in Spain or elsewhere (Israel?) for like $50...

Has anybody done any studies or inspections of the imported R8 arbors? Has anyone seen differences in the unbranded Chinese arbors vs the branded Chinese arbors (Accupro, Jacobs)

FWIW, I have no unbranded or imported R8 collets. Really hoping to find quality US made arbors.
 

eKretz

Diamond; Mod Squad
Joined
Mar 27, 2005
Location
Northwest Indiana, USA
If cost is an issue, I'd watch eBay for some secondhand ones. I'd rather pay a little more than Chinese new price for a good brand name secondhand arbor personally.
 

L Vanice

Diamond
Joined
Feb 8, 2006
Location
Fort Wayne, IN
I bought my R8 spindle mill new in 1974, along with a Jacobs R8-Jt33 arbor and new Albrecht 130-Jt33 chuck. The chuck spun on the Jacobs taper the first time I used it and I quickly realized that I should have bought the Jt6 versions, which have a larger chuck taper. The spinning wrecked the arbor and the chuck part with the 33 taper. I bought a new R8-Jt6 arbor and replaced the chuck part with the Jt6 version. They are still in good shape about 47 years later.

I would trust an Israel-made arbor before a China product, whatever brand. I would not trust any used arbor because they are subject to damage. A NOS Jacobs arbor that is at least 25 years old might be OK but I would not want a new Chinese Jacobs arbor in an old Jacobs USA cardboard tube. Keep in mind that brand names do not guarantee a particular country of manufacture these days.

You would be smart to buy from a source that will give a refund if the merchandise is defective. Test the arbor runout on the Jacobs taper and then check the fit of the taper in the chuck before the final assembly. And final assembly is just that. Do not expect to ever remove the chuck from the arbor. Of course, you will want a good chuck.

Larry
 

AdamC

Cast Iron
Joined
Jun 16, 2011
Location
SE PA
I’m with you guys on not buying China. Been burned plenty of times. Just disappointed I can’t really find US made arbors.

Larry, or anyone else, is there a clever way to check runout of an Arbor using vee blocks on a surface plate? I know the top end is cylindrical, but I think every other surface is a taper. Is there a trick I should know? Like to inspect before I install the arbors in the chucks.
 

Nmbmxer

Hot Rolled
Joined
Jun 22, 2008
Location
VA
I've always used 3/4" straight shanks on as many tools as possible. I've never needed drill chuck with an R8 shank, I can't remember when I spun a chuck in a collet. I don't like having to move the table much (x/y) and avoid z changes when loading a different tool. With a 1" long shank you can usually remove the drill, remove the chuck, then swap collets without having to fool with the knee.
 

hvnlymachining

Aluminum
Joined
Jun 21, 2019
Location
St.Onge
The way I read runout on R8 is mounted in the mill spindle.

1st check spindle runout, mark the high and low location and amount on the spindle with a sharpie.

2nd mount the R8 accessory in question and measure runout where needed on the accessory.

Note location of highs and lows.

3rd, put your math skills to use, adding or subtracting according to the differences between the accessory and spindle runouts.

Simple and also gets you a location mark for alignment of the best possible runout for your spindle/ accessory.

Side note, I bought a Chinese R8-jt6. The jt was way off. The chuck would stick slightly but fall off easily. The chuck and R8 were bought as a set! The chuck taper was close but the R8 wasn't. The runout was bad too. Lesson learned, I had to buy a used Jacobs a few days later.
 








 
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