Inexpensive TTS ER20 Collet Chucks Still Available?

[mcardoso]

Note: This comment is up to date as of March 2019.

I spoke with Mike Li at IGStool.com (sales@igstool.com) and his current offering for TTS compatible tool holders (ordered directly from him) is:

- ER20 with TTS compatible ATC groove 1.38" long 3/4" shank, $17 USD
- Set Screw endmill holders with TTS compatible ATC groove (1/8, 1/4, 3/8, and 1/2"), $18 USD
- FMB22 Face mill holder with TTS compatible ATC groove (looks like a common size for cheap import facemills, 22mm bore), $19 USD

In addition, the related ebay page offers non-ATC geometry collet chucks in the following sets:

- ER20 1 pc., $17 USD + $13 shipping
- ER20 5 pc., $70 USD + $23 shipping
- ER20 10 pc., $120 USD + $50 shipping
- ER16 10 pc., $120 USD + $50 shipping
- ER16 Floating Tap holder (requires modification to work with TTS) $70 + $16 shipping
- ER32 10 pc., $120 + $60 shipping
- ER32 5 pc., $80 + $36 shipping
- ER25 10 pc., $130 + $60 shipping

I've been using these non-ATC ones for a few years (not sure if I got them from him) and have been happy. I don't have an ATC so it wasn't a big deal. The ones I have have runout between .0005 and .0025. The low runout ones are pretty good, but the high runout ones are only good for roughing.

Mike stated that if any chucks were found to have runout exceeding their stated tolerance (<0.01mm = <.0004") they would replace them with new units from their US stock.

I am going to order a few of the ER20 ATC chucks and make sure I get ones with acceptable runout. I will probably then use these most of the time and use my old ones for less accurate tools.

[Steve Seebold]

I looked at the prices and by the time you pay shipping charges they’re almost the same price as buying them hem from Tormach.

[SCzEngrgGroup]

Most of mine (I have about 50, both ER20 and ER32) were made by Darkon:

DARKON™ ER20 ATC Precision Chuck - 4GT.com

I've been very happy with the quality. In fact, they are better made than the genuine Tormach ones.

Regards,
Ray L.

[kstrauss]

I just checked Little Machine Shop (https://littlemachineshop.com/) and they still have TTS holders at the old Tormach price of $39.95 for ER16/ER20, $44.95 for ER32 and $27.95 for screw holders.

[mcardoso]

Keen,

Awesome analysis, thank you. I had planned to inspect these thoroughly as I have an agreement with the seller to replace any chuck out of spec. I used to work in a metrology lab, so I appreciate your method. I intend to check the taper in a vee block. I also own a super precision ER20 collet which I plan to run a mandrel test in the vee block on top of the tests you showed. This should give me an understanding of the combined effects of the taper angle and tolerances of the nut.

The reason behind my selection of an import holder is this. My CNC is not a tormach nor will it likely hold the tolerances that a Tormach would. For me (hobbyist), having a wider selection of pre-chucked tools is a better bang for the shop funds than having a smaller number of higher precision tools. Should the day come where I need to run a small production run of parts, I would go for the Tormach chucks without a thought in my mind.

[mcardoso]

As a note, this particular seller adds his distribution costs to his shipping charges. For 10 chucks I was charged $42 to ship. $35 from China to US and $7 from US to me. This brings the cost per piece to $21. This is still less than half of the Tormach price (before shipping), and cheaper than the Darkon version so I am ok with it. It was either this or have the price already added to the price of the chuck (just a little more surprising this way).

[mcardoso]

Note, This post contains information on chucks received March 2019.

OK, chucks made it in last week. I have mixed feelings about the quality of the product, but I don't regret buying them. Here is my best attempt at an unbiased review. I will make some comparisons between the Tormach TTS tools I have as well as my previously purchased non-ATC chucks.

Shipping and Packaging: Tools arrived within 3 week days from me placing my order via USPS. They were placed inside a double bagged padded Priority Mail envelopes. Each chuck was wrapped in a plastic bag with rust inhibitor and then inside a telescoping plastic tube that tools usually come in. I was a little concerned about damage due to the soft packaging, but there were no issues.

Appearance: The chucks have a nice general fit and finish. The black oxide is dark and even and the machined surfaces of the chuck body are nice. The shank, collar, and OD near the ATC groove of the tool is ground with a fine finish. My previous import chucks had a rough grind to the collar that hits the nose of the spindle, but these new chucks were as smooth as my Tormach tools. The body, threads, and taper of the tool appear to be hard turned. This made me nervous, but shouldn't immediately disqualify precision since hard turning can be as accurate as grinding if done right. The taper had microscopic machining chatter marks (the kind that looks like a mirror shine until you pull out a magnifying glass) but certainly not anything significant enough to cause issues. The taper is smoother than the ground taper on my other imports, but I don't have a Tormach ER chuck to compare against. The threads are burr free and have no chatter.

The collet nuts have a lower quality black oxide and the information is laser engraved on the face. The threads and taper are again hard turned and look quality. Two nuts had poor surface finish/scoring on the taper (likely from a broken tool during manufacturing) and were set aside to be discarded.

Hardness: I used a fine cut file on the back of the holder, near the taper, and on the nut. The file skated across the surface without really biting but did not feel glass hard. I would loosely guess a low to mid 50's Rockwell C scale. A single nut had 5 hardness test dimples present on the face. I did not receive a chuck which had witness marks from a hardness test.

Taper Runout: Chucks were tested by rotating the shank in a Vee Block with a .0005 dial test indicator mounted magnetically to the block. I would have liked to use a .0001 dial indicator, however I did not have a way to measure the taper with this. An extra vee block was used to weight the shank down into the Vee to prevent error due to uneven pressure during measurement. The face of the collar was firmly pressed against the side of the Vee block during the test. This is necessary to keep the indicator in the same location in the taper, however any error in the collar grind will falsely show up as runout in the taper (due to axial motion of the chuck). Chucks and nuts were serialized. Runout was measured at 3 locations within the taper and an average is reported below:

• Chuck 1: .0003” (.008mm) TIR
• Chuck 2: .0003” (.008mm) TIR
• Chuck 3: .0003” (.008mm) TIR
• Chuck 4: .0002” (.005mm) TIR
• Chuck 5: .0004” (.010mm) TIR
• Chuck 6: .0006” (.015mm) TIR
• Chuck 7: .0008” (.020mm) TIR
• Chuck 8: .0008” (.020mm) TIR
• Chuck 9: .0011” (.028mm) TIR
• Chuck 10: .0012” (.030mm) TIR

Assembled Runout: Chuck assemblies were tested using a Techinks 1/4" Precision (.0002" TIR) ER20 collet and a 1/4" carbide dowel seated to full depth in the collet and measured at 3xD (0.75") from the face of the chuck using a .0001" Dial Indicator. The two nuts which were improperly machined were not tested to prevent damage to the collet. Additionally, chucks 7-10 were not tested due to the excessive taper runout. Each chuck was tested with each nut to find combinations that minimized runout. Understand that at least .0002" (if not more) uncertainty in measurement is introduced by the collet, wear on the collet, and the carbide dowel. Chucks were tightly to roughly equal torques, but I do not use a torque wrench, so some uncertainty is introduced there.

Runout varied from .0003" to .0026" with an average assembled runout of .0013". This leads me to believe that either the threads on the collet chucks, or the nuts have machining errors which cause the taper in the nut to assemble off center of the taper in the chuck. I was able to match nuts to chucks 1-5 which gave the following runouts:

• Assembly 1: .0004"
• Assembly 2: .0003"
• Assembly 3: .0006"
• Assembly 4: .0004"
• Assembly 5: .0009"

Repeatability of these matched chuck assemblies unfortunately is not very good. For example, reassembling Assembly 1 yielded the following:

• Assembly 1 Test 1: .0004"
• Assembly 1 Test 2: .0012"
• Assembly 1 Test 3: .0016"
• Assembly 1 Test 4: .0006"

Customer Service: I contacted the seller of these chuck and stated that I had 5 units which did not meet their stated tolerance of 0.01 mm TIR. I explained my measurement method and the results I got. The seller was concerned that my methods may have introduced error in the measurements which was the source of the excessive TIR, but offered to send me 5 replacement chucks immediately. I have not yet received these in the mail, but I am very happy with this outcome.

Closing thoughts: All in all I am happy with the purchase of these collet chucks since my expectations were set reasonably. I have 5 chucks which I can (with a little trial and error) assemble within .0005" or so TIR. For me, having more TTS tools was more important than having 2-3 very precise chucks since I can create a library of pre-assembled tools that I can add to my CAM software. Since I won't need to take the chucks apart nearly as often to swap tools in and out, I can afford to take the time to assemble them for minimum TIR.

If you want less expensive TTS ER20 chucks ($20/ea vs $45/ea) and are willing to take the time to inspect the product and deal with some higher TIR chucks, then I would recommend this product.

[metalmayhem]

Repeatability of these matched chuck assemblies unfortunately is not very good. For example, reassembling Assembly 1 yielded the following:

• Assembly 1 Test 1: .0004"
• Assembly 1 Test 2: .0012"
• Assembly 1 Test 3: .0016"
• Assembly 1 Test 4: .0006"

.

This is likely the difference between a solid nut and a bearing nut . Whats happening is the collet is twisting because of the solid nut , there is a lot of friction . It's not an uncommon occurrence even with high end holders which have a solid nut . This is the main reason why bearing nuts exist .A bearing nut provides much better consistency . The nuts are floating and by right should seat themselves but friction has a funny was of dealing with things . The taper is the precision to be concerned with
A slight bit of lube might help . An easy resolution to the problem is to snug up the collet holder , dial the tool and lightly tap the nut to help it seat properly in position . Tighten then check it again .
The common argument to the resolution is " I won't hammer on precision tooling " , which is ridiculous because it's hardware and it doesn't require a 5lb hammer . We tap vises , parts etc into place .
Reason I mention this is that I've heard the argument too many times , but it's an old trick that works and saves a lot of grief

In your dial tests , did you check to see if the pin is running parallel to the holder shank

[mcardoso]

That's great advice. I could pick up a few bearing nuts to try them out as well.

Couldn't run the indicator along the tool on the setup I used but I would happily check a few to see. I did take runout measurements at varying lengths from the chuck and found them fairly consistent with the measurements closer to the chucks. There is some angular misalignment of the tool to the chuck, but not much compared to the radial runout. Try to get some real numbers to back up that statement.

[metalmayhem]

I'd recommend trying what I suggested before buying bearing nuts . The inconsistent results are a good indication of binding . A lot of the time it only takes one tap with a hammer to knock everything in place . The whole point of the nut is to force the collet into the taper which is where the precision alignment is . The nut threads are loose and there really isn't much precision to the nut other than the taper . This allows a lot of play for what should be proper alignment of the collet , but the binding is what will throw things out of wack .

I have about 40 of the cheap ebay holders and I can have them run dead-nuts without much problem , and thats with the cheap ebay collets

[mcardoso]

Thanks for the advice. I will try to do that!

[MFchief]

No dog in this fight, but bearing nuts are expensive, cheapest I've seen are Shar's at about 20 bucks. That gets you back to why buy a substitute collet?

Terry

[mcardoso]

Got the 5 replacement chucks from the post above. They are completely different from the first 10 as far as physical appearance. They are about 1/8" longer, have more black oxide, a thinner contact ring on the collar, and ground tapers (rather than hard turned). I think the physical appearance is a little worse than the other 10, but all ran true within .0003 checked at 3 places in the taper. I'm happy. So now I have 24 ER20 collet chucks with maybe 6 or 7 that are only good for drilling or roughing tools.