Duhadaway Tool
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04 · Spindle and drawbar · Newark, DE

No spindle bearing quoted without its class and contact angle.

Matched pairs of angular-contact CNC spindle bearings at P4 / ABEC 7, CAT40 and BT retention knobs, and drawbar spring stacks. Sold to shops and rebuilders who already know what is inside the cartridge. We supply the parts. We do not rebuild the spindle.

Bearings: per matched pair Knobs: per piece Quoted on inquiry
Ask for a spindle parts quote (302) 366-0113
A spindle cartridge taken apart with bearings and spacers laid out in order
Laid out in teardown order. Spacers stay with the bearings they came between.

Precision class, in plain words

P4 and ABEC 7 are the same tolerance band, written two ways.

ISO calls it P4. The American ABEC scale calls it 7. Either way, it governs how round and how concentric the rings run. It says nothing about the contact angle, and that is the part people leave off.

Precision class equivalents and where each belongs
ISO 492ABECTypical useDo we quote it
P0ABEC 1Motors, fans, conveyorsNo. Wrong page
P5ABEC 5Lathe tailstocks, some older spindles by maker specWhere the machine calls for it
P4ABEC 7Machining centre and lathe main spindlesYes. The default here
P2ABEC 9Grinding spindles, very high speedOn request, long lead

15° contact angle

Takes less axial load and runs faster. You find it on high-RPM spindles, 12,000 and up, where heat is the enemy and the cuts are light. Put a 15° set into a spindle built for 25° and it will run, for a while, then go loose under a heavy face-mill pass.

25° contact angle

Stiffer axially and slower. The usual choice on geared-head and belt-drive spindles taking heavy roughing cuts in steel. The markings on the outer ring usually carry a letter for the angle: C for 15°, E for 25° in most catalogues. Read it off the old bearing and send it.

Two items · each quoted on inquiry

What goes inside the cartridge and what pulls the holder in.

Item 04.1
A matched pair of angular contact spindle bearings on a clean cloth

Sold as the pair. Never split, never mixed with the old set.

Angular-contact spindle bearings · matched pair

Angular-contact spindle bearings, P4 / ABEC 7.

Precision angular-contact ball bearings supplied as matched pairs, universally ground or in the set arrangement your spindle drawing shows: back-to-back (DB), face-to-face (DF) or tandem (DT). Steel balls by default. Ceramic hybrid where the original was hybrid.

We need four things before a quote goes out: the bore, the outside diameter, the width, and the markings off the old outer ring. From those we read precision class, contact angle and preload. If the ring is too worn to read, the machine make, model and spindle serial will usually do it.

We will not quote a spindle bearing without its precision class and contact angle. A pair that fits the housing and has the wrong angle is a second teardown waiting to happen.

Precision
P4 / ABEC 7 (P2 on request)
Contact angle
15° or 25°, as the spindle specifies
Arrangement
DB, DF, DT or universal matched
Preload
Light, medium or heavy per original
Match by
Ring markings, or bore × OD × width plus machine model

Price basisPer matched pair, quoted on inquiry. Hybrid ceramic and P2 sets cost substantially more than steel P4.

Lead time stated on the reply, by size and class

Ask for a spindle parts quote
Item 04.2
A worn retention knob beside a new one, with a stack of drawbar springs

Left: fretting on the gripping face. Right: what it looked like new.

Retention knobs and drawbar springs

Retention knobs and drawbar springs.

Most spindle crashes we hear about start with a pull stud nobody replaced. They cost less than an hour of downtime. A retention knob is a small forged and hardened part that holds the whole holder in the taper, and it is the part that gets forgotten until a holder drops out mid-cut.

Retention knobs for CAT40 and BT30 / BT40 come in several profiles: ANSI (CAT), MAS 403 for BT, and a range of maker-specific angles, 45°, 60° and 75°, with or without a through-coolant bore. The gripper in your drawbar is made for one of them. That is why we specify by machine model and not from a photo alone. Two knobs can look identical and differ by 15° under the head.

Drawbar springs are Belleville disc stacks. They lose force over millions of tool changes. If holders are pulling out with chatter marks on the taper, test the drawbar force before you blame the holder. We supply the stack by count and orientation off the original.

Knob profiles
ANSI (CAT40), MAS 403 (BT30, BT40), maker-specific
Head angle
45°, 60° or 75° by drawbar
Coolant
Solid or through-bore
Springs
Belleville stacks, count and orientation to original
Match by
Machine make, model and serial

Price basisPer knob or per spring stack, quoted on inquiry. Knobs are cheaper by the dozen and you should buy them that way.

Lead time stated on the reply, by profile

Ask for a spindle parts quote

When to replace a retention knob

Look at the gripping face, not the thread.

Pull a holder from the carousel and look at the underside of the knob head under a good light. Bright polished rings, fretting, or a lip rolled over at the edge mean it is done. So does any crack at the neck. Replace, don't dress.

  • Torque the knob to the maker's figure with the holder in a proper tightening fixture, not in the vise.
  • Clean the thread and face before fitting. A chip under the flange puts the knob off-axis.
  • Many shops replace knobs on a schedule rather than by inspection. Ask your machine builder for their interval.
  • Never mix profiles in one carousel. One wrong knob in forty holders is how a holder ends up on the floor.

Holders themselves live on the toolholding page, with the pull-stud thread matched to the drawbar.

What happens after you ask

From the old ring markings to a matched pair on your bench.

  1. Send the markings or the dimensionsA photo of the outer ring face, or bore, OD and width in mm. For knobs, the machine make, model and serial plate.
  2. We read class, angle and preloadIf any one of them is missing we ask before we quote. That can add a day. It saves a teardown.
  3. Reply with part number and basisThe standard part, its typical lead time, and a price basis by phone or email. Not binding until you confirm.
  4. Ships sealedBearing pairs leave in the maker's sealed packaging with the matching marks intact. Open them in a clean room or on a clean bench, not beside the saw.

We do not rebuild or repair spindles, and we don't press bearings. If you are not equipped to set preload and run the spindle in, send the whole cartridge to a spindle rebuild shop. They can buy the pair from us or from anyone.

Heavy cuts wear bearings. Check what your next pass asks of the spindle.

Open the cut-load calculator

Objections we hear

Straight answers on spindle parts.

Can I replace just the one bearing that sounds bad?

No. Matched sets are ground together for preload. One new bearing against one worn one gives you neither the stiffness nor the life. Replace the set.

The markings are gone. Can you still match it?

Usually, from the machine model and spindle serial plus measured dimensions. If the builder used a special bearing we'll tell you it needs to come from them.

Are CAT40 and BT40 retention knobs interchangeable?

No. Different thread, different profile. A CAT40 knob is 5/8-11. A BT40 knob is M16. And within BT there are several head angles. Tell us the machine.

Who should not buy from this page?

Anyone hoping to fix a noisy spindle without the tools to set preload. Buy the rebuild, not the parts.

Same machine, other assemblies

Related parts on the catalogue.

Parts desk

Ask for a spindle parts quote.

801 DAWSON DR
NEWARK, DE 19713

Email a photo of the outer ring markings to the address above if the form won't take it.

Bearings, knobs or drawbar springs

Inquiry only. A price basis comes back by phone or email and nothing is binding until you confirm.

Or call (302) 366-0113 with the old bearing in your hand.