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Introduction
One Week Later
thought
. The booklet that accompanied the Grizzly chuck specified that the mounting dimensions would fit my spindle perfectly.One Week and One Day Later
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Most lathe tooling inventories include several 4-jaw chucks of different diameters and they are used often. These are good workholders and indispensable for certain needs. I'm more appreciative of scroll chucks if concentricity to existing diameters is not critical. My lathe spindle isn't cam-lock or threaded so it's time-consuming to change workholders.I've wanted a 6-jaw scroll chuck for many years. Good ones are superior to 3-jaw and 4-jaw chucks in gripping power and always superior to 3-jaws regarding concentricity and repeatability. These devices are hard to find for small lathes like my Emco "Compact Eight". The "set-true" configurations - the most desirable ones - start at 6 inches in diameter, too large for an eight inch lathe.Imported 4 inch diameter, 6-jaw chucks are available but aren't the "set-true" design. Hardened jaws common to most scroll chucks aren't easily modified for the addition of adjustable "soft" jaws. Nevertheless I decided to order and evaluate one of these imports with the eventual idea of modifying the chuck to add adjustable jaws.Importers provide sparse information about chucks and backplates; it's confusing to mate the two at long distance. The allusion, generally, is that a backplate WILL be required but not much help is provided to select it if one doesn't happen to own a standard configuration spindle. I ordered "my" chuck without a backplate because there "may" be advantages:1. Given a fortunate combination of chuck and spindle dimensions, the chuck can itself be modified to fit the spindle (with a LOT of luck it might even fit without modification … this will be discussed again later).2. Modifying the chuck can save money and provide greater accuracy because overhang is reduced, reducing the cumulative errors of spindle, backplate and chuck. There are techniques that minimize accumulated inaccuracy but they are ineffective if the scroll of the chuck is not precise - more on this later. The four inch 3-jaw chuck that is usually mounted on my lathe has no backplate and has given almost forty years of acceptable service.3. Blank backplates are expensive ! It's likely that one has a piece of steel plate suitable for making a backplate, provided that the time is available to do so. In my particular case, a blank backplate would cost about $70 while the material to make one would cost $16. Making a backplate is straightforward work and takes an hour or two.4. Improving chuck performance: for example, by designing/making a configuration that allows adjustment of the chuck to the backplate, "tuning" the chuck performance for specific diameter ranges (if the jaws cannot be adjusted).When the chuck is received and disassembled, I'll be able to decide the next step. Anticipation is fun since it also allows for planning alterations, sequences of operations and so forth. It should be noted that when imported Asian products are ordered the anticipation takes on added spice. Chinese products can be a "grab bag" - one is never quite sure what will be delivered compared to what was ordered, LOL.The Big Brown Truck arrived at 6:00 PM (we are the last stop of the delivery route) with the "Grizzly" chuck. After opening the package, I noted that the chuck doesn't look anything like the illustration in the catalog or the website (refer to the last sentence of the previous paragraph). Here's the online illustration, from which I based my purchasing decision:This is what I actually received:There are no stepped jaws, which SERIOUSLY limits the versatility of this device. One of the main reasons for owning a 6-jaw scroll chuck is the ability to grip - internally - thin tubular workpieces, spreading the load more effectively with less distortion than 3-jaw and 4-jaw workholders. This chuck cannot grip ANY internal features.Additionally, the separate set of external gripping jaws - a standard feature with scroll chucks - was not included. The booklet that accompanied the chuck listed the extra jaws as included parts. (For those who may not know this, the jaws in scroll chucks are not reversible, as are those in independent chucks.)Another disadvantage of the "no-step" jaw configuration is that several modifications that I'd envisioned to obtain adjustability are impossible. (While waiting for delivery of the chuck, I'd conceived a couple of schemes for attaching adjustable soft jaws to the stepped jaws that were "supposed" to ship with the chuck.)Modifying any chuck would be a simple process if the jaws weren't hardened. Even so, jaws can be annealed, machined to suit and re-hardened but there is risk of distortion (more like a certainty). Finish grinding jaw contours may not be difficult but distortion of the scroll interface is a different proposition !(That is the problem with ANY scroll chuck. It's possible to true the jaws of inexpensive chucks very accurately but ONLY to one specific diameter and only when the adjustment pinions are tightened to a specific torque. The key to accuracy and concentricity is the scroll and it's hard to imagine a more difficult geometrical configuration to produce ! The main cost of quality scroll chucks and particularly the 6-jaw variety, is probably the cost of making a precise scroll. Making these requires a universal milling machine with geared dividing head although modern scrolls are probably made on a CNC vertical mill.)Another possibility for re-configuring jaws might include plasma cutting to rough shape and then finish grinding, but the risk of distortion is still significant. The least desirable alternative would be rough-milling the steps with a carbide cutter then grinding to dimension in the lathe. Although I do occasionally mill hardened steel, the risk of expensive tool breakage is high when using a vertical mill, a very "rubbery" kind of machine. The feed rate must be very slow and I really wouldn't care to spend a day milling six hardened jaws.From the photo of the chuck that Grizzly shipped, it can be noted that the tapered jaws are twice the length of the stepped jaws shown in their ad photo. The extra gripping length would seem to be desirable but the tradeoff is additional overhang. The face of the workpiece would be about twice the distance from the chuck face as my old veteran 3-jaw. If the jaws are axially true with the mounting feature then the problem might simply be one of diminished rigidity (more on this later).When short workpieces are gripped frequently, long chuck jaws are not the best workholder. They will "bell-mouth" more rapidly than strong, stubby jaws - not necessarily just from jaw distortion but also from slight amounts of scroll distortion and keyway wear multiplied by the distance of the workpiece from the scroll. One might make an argument that the extra gripping power and rigidity of the 6-jaw outweighs this shortcoming - that would be a complicated analysis. It's really a question of the benefit of longer jaws versus the drawback - in other words, what work will normally be held in the chuck ?Speaking of "grip", the jaws on the Grizzly chuck are perfectly smooth. (It's the first chuck I've ever seen like this except for "commutator chucks" with bronze jaws used specifically as a bearing surface - sort of a steady rest residing in tailstocks of lathes set up for electric motor work.) Tradition, for good reason, suggests that jaws of workholding chucks (not drill chucks) be serrated to increase holding power and the Grizzly ad photo shows serrated jaws. It's not a huge drawback, fifteen minutes skillful work with a diamond wheel in a Dremel tool can correct this but it is another example of cost cutting irritation.(Possibly one of the reasons that Chinese imports are frequently referred to as "assembled kits".)The chuck was delivered with a booklet of "operating instructions" (?!) and an inspection sheet "signed" by three different people with the same handwriting. Unhappily, none of the sixteen critical measurements (jaw runout, body runout, face perpendicularity and mounting dimensions) were measured. I shouldn't say that they weren't measured, I don't know that.It IS accurate to note that no measurements were RECORDED. The booklet provided was written for a 3-jaw chuck, not a 6-jaw chuck. The model number stamped on the face of the chuck didn't match any of the model numbers in the booklet. Most of the measurements were related to the various clamping positions of the STEPPED jaws which do not exist on the chuck that I received so any recorded measurements would have been a deception anyway.Why am I perpetually amazed by the difference between what I order and what I receive, LOL ?I should know by now to calibrate my expectations accordingly when buying imported products. But where else can we buy some of these tools ? American and (many) European products have disappeared from price-cutting. The result is that quality standards are established by the seller because an effective monopoly exists."Grizzly" and other importers also influence quality standards by influencing manufacturers to design to a specific price goal. Something has to slip in terms of quality or capability. There is little point in complaining to importers about these "slight" discrepancies. The buyer's reluctance to return goods is factored into their business plan. And to be fair, the importer is also somewhat at the mercy of the factories in China …This is the classic quandary that the HSM purchaser, with little economic leverage, encounters. We purchase machinery with an expectation of performance that is neither guaranteed nor stated - it is rarely even implied. After waiting for some time and paying substantial shipping costs, we might unpack a machine, get it into service (sometimes taking several days) and find that the machine doesn't perform to expectation. What's next?Repack the machine (probably having to rent or borrow - AGAIN - the engine hoist or forklift that was used to set it up), pay AGAIN for a shipper to pick it up and return it to the importer. And then pay the importer a "re-stocking" fee ? This is a perfect storm that benefits only the seller. (In this case, the ending wasn't so bleak as you'll discover.)The biggest bite for home machinists is the difficulty of paying for and moving large machinery which results in a reluctance to complain and return unsatisfactory products to the importer. This is probably a result of inexperience regarding the moving/rigging process, of course, which is universal when those lacking knowledge decide to make this "hobby" their own. I suspect that the importers and distributors know this and take advantage of the fact.There was ONE bright ray of sunshine in this chuck experience, I. The booklet that accompanied the Grizzly chuck specified that the mounting dimensions would fit my spindle perfectly.But NO - when I measured the rear of the shuck, I found that the bore diameter was far larger than the lathe spindle spigot and the mounting holes were on a different bolt circle (and had different threads). Oh well, the experience so far has been consistently negative. Here is a photo of the back of the 6-jaw, beside it is an old aluminum backplate (for a small 4-jaw) depicting the correct dimensions:I decided to spend just a little more time reviewing the chuck (so that others might benefit from my purchasing error). I disassembled the chuck for cleaning and inspection, noting that the internal details and workmanship were as good as a Polish-made Bison chuck that I had occasion to take apart a few months ago. There were no chips or foreign debris in the internal mechanism just the greasy preservative with which the chuck was protected. (The alloys used are obviously unknown.) Frankly, the details were far better than I had a right to expect for the purchase price.After assembling and engaging all six jaws in the scroll then rotating the adjustment pinions two full turns, I measured the largest diameter this chuck could support at 1-1/4 inches. Scrolling the jaws closed, I measured the smallest diameter the chuck could grip at 3/32 inch. The notable characteristics are:1. The chuck cannot grip any inside diameter: a pipe, a tube or anything with a bore2. The chuck can ONLY grip outside diameters from 3/32 to 1-1/4 inch3. 5C collets can do anything that this chuck can do and do them betterBy the way, although none of the extra parts that were described in the booklet actually came with the chuck, it DID come with a bright red wash-cloth which you can see in the following photo, taken after the chuck was disassembled and cleaned.Runout was measured in the lathe by first turning a shaft (about ten inches long) true to the spindle axis and the tailstock center. The shaft was indicated before mounting the 6-jaw, confirming no radial runout (the shaft diameter was approximately 1/2 inch which is near the center of the adjustment range). After withdrawing the tailstock, the 6-jaw was slipped over the shaft and tightened, one pinion at a time. The tailstock was then re-engaged and tightened.Measured runout at the mounting bore (and the outside diameter of the chuck) was .0025. The test was repeated three times using different techniques including gripping the end of the shaft with a "known good" 5/8 drill chuck in the tailstock. No runout improvement was noted in any of the setups compared to the first measurement.I was curious to see how my old 3-jaw chuck performed compared to this new 6-jaw. I measured the runout of a 1/2 inch ground drill rod next to the chuck jaws at .0005 inch and at 3 inches from the jaws at .0025 inch. The booklet enclosed with the 6-jaw chuck specified .0030 runout at the same distance from the face. So the new chuck, offers no advantage over the forty-year old 3-jaw except in gripping power and the ability to spread the chuck pressure over the workpiece.Additionally, the 6-jaw has limitations of capacity and the inability to hold inside bores. The old 3-jaw chuck can grip outside diameters from 1/32 to 4 inches and inside diameters from 1-1/2 to 4 inches. Larger diameters than these are limited by the swing over the carriage, not by the chuck.Returning this tool will require approval by Grizzly - it may be difficult to obtain since there are no published specifications for the chuck in their catalog or on their website. I'll be interested to hear their response to my initial complaint and will post it here. If they won't allow me to return the product then there are a couple of backup plans that can improve performance.No response from Grizzly after two e-mails. The first e-mail was sent on a Friday evening and the second the following Monday afternoon. To be fair, they haven't had much time to absorb my complaint and respond.Sent a third e-mail to Grizzly this morning and received a telephone call two hours later from a customer service representative. He said that he had requested the warehouse to open one of the shipping containers for the 6-jaw chuck and that the tool indeed had the deficiencies noted in my description. The representative asked how quickly I could pack the chuck, I told him that it was packed already. I was given a RMA (returned material authorization) number and told that UPS would pick up the chuck from my house - no shipping charges. That's a happy ending to this story - the happiest one that I could have anticipated after realizing that the chuck couldn't suit my needs.Still waiting for the happy ending … sent another e-mail to the customer service representative.Still waiting … got an e-mail from Grizzly counseling patience.Still waiting …Still waiting … patience wearing thin.Wondering about the highly publicized Grizzly customer service.E-mailed another complaint to Grizzly.Grizzly e-mailed back: another UPS pickup request has been issued.Still waiting …Still waiting ... I received a call from Grizzly this morning, wanting to know if my address was correct. Since they had successfully shipped the chuck to this address and successfully billed me at this address, picking the chuck up from the same address should not present a challenge, right ?An earlier e-mail from the same person implied - without actually stating it - that perhaps nobody was home when "they" tried to pick up the part. That seems to be an evasion of responsibility or an attempt to blur the responsibility and I responded by stating that it is also not true. You'd think that importers of Chinese products would have their act together when it comes to returns, since a large percentage of their products either get returned or require replacement parts !At last … it's GONE ! Now comes the part about crediting me for the chuck that I already paid for, LOL !Thanks for being patient with my story. I started writing the evaluation a few weeks back and I can't recall why I felt so good about the project at the beginning. This started out optimistically but each successive discovery seemed to represent hundreds of other stories that I've read (here and elsewhere) about customer dissatisfaction with imported products. But what are we to do since there are few alternatives left to us outside China ?Randy C
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