Zero parameter rows and three code strings
The parameter block on this listing is empty. The description is the title repeated, followed by four headings with nothing under them: Product Overview, Packing Shipping, Corporate Information, FAQ. Every number a buyer could use is inside the product title, and the title gives three strings separated by asterisks: F68*G42*D30, F58*G20*D10*A25 and F76*G35*D25.
None of the eight gallery images carries a dimension drawing. Five are photographs of the block, one shows four variants side by side, one is a shipping-services banner and one is the company gate. So the only specification on the page is twelve letters and nine numbers, with no units and no model number.
This article takes those three strings seriously and tries to decode them against the standard that governs this class of tooling. The conclusion is blunt: four of the nine numbers land on a standard value, and the letter D points at three different dimensions in the same title.
What the title actually claims
Read literally, the title says the listing sells a tool holder identified by three dimensional strings, and that all three belong to the same product. That is the first problem. A single tool holder has one locating bore, one centre height and one shank. Three different strings cannot all describe one block unless the block has three different interfaces, which no turret station can accept.
The alternative reading is that the listing sells a family and the title lists three members. That reading is plausible, since the sibling listings in the same queue name a model number (HAK31080, HAK31100) rather than a string. But a family listing still has to tell the buyer which member is which, and this one does not.
The standard these codes do not follow
Turret tool holders of this shape are covered by DIN 69880, now also published as ISO 10889. A conforming holder is designated by form, size and tool interface, in the manner of E4-30xER25: form E4, size 30, ER25 collet. The designation carries the size explicitly and the interface explicitly.
F68*G42*D30 is not that syntax. There is no form letter followed by a size followed by an interface. There is a letter, an asterisk, a number, repeated. A buyer cannot map it to a turret station without asking, and the page has no channel for asking except the enquiry box.
Seven dimensions hide behind one number
The reason a single number is not enough is that a VDI interface is defined by seven coupled dimensions. They are not independent choices; they move together with the size.
| VDI size | Shank dia. | Locating bore | Retention knob | Face contact | Bolt circle | Bolt | Centre height |
|---|---|---|---|---|---|---|---|
| VDI 20 | 20 mm | 26 mm | 8 mm | 34 mm | 32 mm | M5 | 40 mm |
| VDI 30 | 30 mm | 38 mm | 10 mm | 50 mm | 45 mm | M6 | 52 mm |
| VDI 40 | 40 mm | 50 mm | 14 mm | 65 mm | 58 mm | M8 | 65 mm |
| VDI 50 | 50 mm | 62 mm | 16 mm | 80 mm | 72 mm | M10 | 80 mm |
| VDI 60 | 60 mm | 76 mm | 20 mm | 95 mm | 88 mm | M12 | 95 mm |
Say a holder is VDI 30 and stop there. You have named the shank diameter. You have not named the 38 mm locating bore, the 10 mm retention knob, the 50 mm face contact, the 45 mm bolt circle, the M6 bolts, or the 52 mm centre height. Get any one of those wrong and the holder does not seat, or seats and cuts off-centre.
Decoding the three strings against the standard table
Set the nine numbers beside the standard values. A number counts as a match only if it equals a published DIN 69880 dimension for some size, which is a weak test: it shows the number is plausible, not that the reading is right.
| String in the title | Token | Value | Matches a DIN 69880 value? |
|---|---|---|---|
| F68*G42*D30 | F | 68 | No standard dimension has 68 |
| G | 42 | No standard dimension has 42 | |
| D | 30 | Yes: shank diameter of VDI 30 | |
| F58*G20*D10*A25 | F | 58 | Only as the VDI 40 bolt circle |
| G | 20 | Yes: knob of VDI 60, or shank of VDI 20 | |
| D | 10 | Yes: retention knob of VDI 30 | |
| A | 25 | No standard dimension has 25 | |
| F76*G35*D25 | F | 76 | Yes: locating bore of VDI 60 |
| G | 35 | No standard dimension has 35 | |
| D | 25 | No standard dimension has 25 |
Four numbers survive that weak test. F76 equals the VDI 60 locating bore. D30 equals the VDI 30 shank. D10 equals the VDI 30 retention knob. G20 equals either the VDI 60 knob or the VDI 20 shank, which is itself an ambiguity.
Read those four together and they contradict each other. F76 points at VDI 60, the largest size in the table, whose centre height is 95 mm and whose bolt circle is 88 mm. D30 points at VDI 30, whose centre height is 52 mm and whose bolt circle is 45 mm. One string in one title appears to describe a VDI 60 bore and a VDI 30 shank at the same time.
The letter D means three different things in one title
This is the part that makes the strings unusable rather than merely terse. D30 reads as a 30 mm shank, which is VDI 30. D10 reads as a 10 mm retention knob, which is also VDI 30 but a different feature. D25 does not match any standard dimension at all.
So the same letter, in the same title, denotes a shank in one string, a pull-stud diameter in the second, and an unknown quantity in the third. There is no reading under which the three strings form a consistent code. Either the letters are shop-floor shorthand that only the seller decodes, or they are dimensions in a house numbering scheme that is not published anywhere on the page.
For a buyer this is not a cosmetic problem. A 30 mm shank and a 30 mm tool bore are different purchases. One mounts the holder to the turret, the other accepts the boring bar.
The carton in image 4 says 25
The fourth gallery image is a bench photograph. Behind the holder, on a cardboard box, a printed label reads kong 25 liang yong, that is, a 25 mm bore, dual use. That is the only external evidence on the page about the tool bore, and it disagrees with the title, which offers D30, D10 and D25 in the same breath.
A carton label is not a specification. It is a packing mark, applied by whoever packed that particular box, and it may describe one variant among several. But it is still the closest thing to a statement of bore size anywhere in the eight images, and it is 25 mm, not 30 mm.
What a 25 mm bore decides
The bore sets the largest boring bar the holder can clamp, and the stiffness of that bar scales with the fourth power of its diameter. Going from a 16 mm bar to a 25 mm bar is not a 56 percent improvement; it is a 5.96-fold improvement in bending stiffness, because (25/16)^4 = 5.96.
That is why the bore is the number worth arguing about. A 25 mm bore and a 30 mm bore look interchangeable on a spec sheet and are not: the 30 mm version accepts a bar with (30/25)^4 = 2.07 times the stiffness of the largest bar the 25 mm version takes. On a long boring pass that difference shows up as chatter, and chatter shows up as a tapered bore.
It also sets what you cannot do. A 25 mm bore cannot take a 32 mm bar at all, no matter how rigid the block is. Buyers who plan to grow into larger bars should size the bore for the largest bar they expect, not the one they use today.
Centre height, and why one size step matters
Centre height is the dimension most often assumed and least often checked. It steps with the VDI size, and the steps are large.
| Step | Centre height | Bolt circle | Locating bore | Shank |
|---|---|---|---|---|
| VDI 30 to VDI 40 | +13 mm | +13 mm | +12 mm | +10 mm |
| VDI 40 to VDI 50 | +15 mm | +14 mm | +12 mm | +10 mm |
| VDI 50 to VDI 60 | +15 mm | +16 mm | +14 mm | +10 mm |
A 13 mm jump between VDI 30 and VDI 40 is not a tolerance. On most turrets the tool height is set by shims or by a height-adjustment screw with a few millimetres of travel, not thirteen. If you own a VDI 30 turret and fit a VDI 40 holder, the tool sits 13 mm high and no shim kit will bring it back.
What a centre-height error does to a turned diameter
A tool set e millimetres above centre does not cut the diameter you dialled. It cuts a diameter larger by 2(R - sqrt(R^2 - e^2)), where R is the radius being turned. The error is worst on small work.
| Work diameter | Tool 0.5 mm high | Tool 1.0 mm high | Tool 13 mm high |
|---|---|---|---|
| 10 mm | 0.050 mm oversize | 0.202 mm oversize | No cut possible |
| 20 mm | 0.025 mm | 0.100 mm | No cut possible |
| 50 mm | 0.010 mm | 0.040 mm | 7.292 mm oversize |
| 100 mm | 0.005 mm | 0.020 mm | 3.439 mm |
| 200 mm | 0.003 mm | 0.010 mm | 1.697 mm |
One millimetre high on a 10 mm diameter leaves the part 0.202 mm oversize, which is 20 percent of the error and far outside a normal tolerance. The same millimetre on a 200 mm diameter leaves 0.010 mm, which most shops would never notice. And 13 mm high on a 20 mm diameter does not cut at all: the tool is above the top of the work.
This is the practical cost of an ambiguous code. The failure does not look like a wrong part. It looks like a lathe that will not hold size on small diameters, and the search for the cause starts at the spindle, not at the tool block.
Four listings, one product family
This is not the only listing for this tooling in the queue. Four listings carry the same block.
| Queue index | What the title leads with | Model named | Parameter rows |
|---|---|---|---|
| 280 (this listing) | F68*G42*D30 | None | 0 |
| 419 | HAK31080 end cutter holder 42*75-16 | HAK31080 | 0 |
| 485 | F68*G42*D30 and F71*G43*D25*A40 | HAK31100 | 0 |
| 498 | F68G*G42*D30*A25, double water inlet | None | 0 |
F68*G42*D30 appears in three of the four. Only two of the four name a model number at all, and they name different ones: HAK31080 and HAK31100. A buyer comparing the four listings has no way to tell whether HAK31080 and F68*G42*D30 are the same object, two sizes of one object, or two objects.
Nine shared images across four listings
Comparing the eight gallery images of each listing by file hash gives nine collisions. Listing 280 shares three of its eight images with listings 485 and 498. Listing 419 shares three with 280, and three with 485. Listing 498 shares four with 485.
Shared photography is normal for a product family sold from one workshop. It does become a problem for the buyer when the photographs are the only specification: if four listings share the same bench photograph of the same block, that photograph cannot tell you which bore the block in your carton has. The carton label in image 4 is doing work that a dimension drawing should be doing.
What the photographs do show
Credit where it is due. The photographs are clear and they do establish several things that the parameter block omits.
- The block is a machined steel body with a rectangular section and chamfered top corners, not a casting.
- Four mounting holes are visible on the face, matching the four-bolt circle of a VDI interface.
- Two hex-socket clamp screws sit above the tool bore, so the bar is clamped by direct screw pressure on a split block rather than by a wedge.
- Two orange O-ring ports sit below the bore on the front face. Listing 498 calls this a double water inlet, and the photograph agrees.
- A locating key projects from the base, which is what registers the holder rotationally in the turret slot.
- The bore is through-drilled and appears to be plain, with no reducing sleeve fitted in any photograph.
None of this tells you the bore diameter, the centre height, the bolt circle or the material. It tells you the architecture, which is useful for recognising the part and useless for ordering it.
What to measure before ordering
Do not start from the title. Start from the turret and work outward. Four measurements settle almost every ambiguity.
- Shank diameter at the turret face. 30, 40, 50 or 60 mm. This picks the VDI size and therefore five other dimensions at once.
- Locating bore diameter in the turret. A VDI 30 turret has a 38 mm bore. If you measure 38, you need a VDI 30 holder regardless of what any title says.
- Bolt circle and thread. Centre-to-centre across two opposite holes, and the thread in them. VDI 30 is 45 mm on M6; VDI 40 is 58 mm on M8.
- Centre height from the turret face to the spindle centreline. Compare with 52 mm for VDI 30 and 65 mm for VDI 40. If the holder you are offered does not match, it is the wrong holder.
Then decide the tool bore from the largest bar you intend to run, not from the smallest. The bore is the one dimension on this part that cannot be shimmed, sleeved downward, or adjusted at the machine.
What to put in the request for quotation
The listing cannot answer the questions that matter, so the enquiry has to ask them explicitly. Ten items cover the part.
| Item to confirm | Why it decides the part |
|---|---|
| VDI size, as a number from the turret plate | Fixes shank, bore, bolt circle, bolt thread and centre height at once |
| Locating bore diameter | A VDI 30 needs 38 mm; 30 mm will not seat |
| Bolt circle and thread | VDI 30 is 45 mm on M6; a 58 mm circle is VDI 40 |
| Centre height of the holder | VDI 30 is 52 mm, VDI 40 is 65 mm; a 13 mm step is not adjustable |
| Retention knob diameter | VDI 30 uses 10 mm; the pull stud must engage it |
| Tool bore diameter and its tolerance | Sets the largest boring bar, and whether a reducing sleeve is needed |
| Clamping method: screw, wedge or split block | Decides repeatability when a bar is swapped mid-batch |
| Coolant: through-tool, twin inlet, or none | The photographs show two O-ring ports; confirm both are drilled through |
| Material and heat treatment | Not stated anywhere; case hardness governs bore wear |
| Drawing, dimensioned, with the bore and centre height called out | The only document that resolves the three strings |
The last item is the one that ends the ambiguity. A dimensioned drawing with the bore and the centre height called out turns three code strings into a part you can inspect on arrival. Without it, the carton label is the specification, and a carton label is not a specification.
The short version
This is a steel VDI-pattern turret tool holder with a through bore, two clamp screws, a locating key and twin coolant ports. The photographs show it clearly. What the listing does not do is tell you which size it is, and the three code strings in the title do not resolve to a consistent VDI size: F76 points at VDI 60, D30 points at VDI 30, and the letter D carries three different meanings in one line.
Buy it from the turret outward. Measure the shank, the bore, the bolt circle and the centre height, pick the VDI size from those four numbers, and only then choose the tool bore from the largest bar you plan to run. Ask for a dimensioned drawing. If the seller can supply HAK31080 or HAK31100 as a named model, ask which of the three strings that model corresponds to, because the page does not say.
Frequently asked questions
What does F68*G42*D30 mean on a CNC turret tool holder?
It is not a DIN 69880 or ISO 10889 designation. Of the three numbers only 30 matches a standard dimension, the VDI 30 shank diameter. 68 and 42 match no published VDI dimension, so the string cannot be decoded from the standard and has to be confirmed with the seller.
Is this a VDI 30 or a VDI 40 tool holder?
The page does not say. D30 suggests VDI 30, but F76 in the same title equals the VDI 60 locating bore, and one of the sibling listings names HAK31100. Measure the shank at the turret face and the locating bore: 30 mm shank with a 38 mm bore is VDI 30, 40 mm with 50 mm is VDI 40.
Why does centre height matter more than the bore size?
Because it cannot be adjusted. A bore that is slightly large can be sleeved down; a holder whose centre height is 13 mm off, the step from VDI 30 to VDI 40, cannot be shimmed back on most turrets. One millimetre high already cuts a 10 mm diameter 0.202 mm oversize.
The carton label says 25. Is the bore 25 mm?
It is the only bore figure in the eight images, printed on a box behind the holder in image 4, and it reads 25 mm dual use. It is a packing mark, not a drawing. Treat it as evidence that a 25 mm variant exists in this family, and confirm the bore for the specific unit you are buying.
What is the double water inlet visible in the photographs?
Two O-ring ports on the front face below the tool bore, which listing 498 describes as a double water inlet. Confirm both are drilled through to the bore and that the O-ring size matches your coolant coupling, because a port that stops short is a port that leaks.
Can I use a 32 mm boring bar in this holder?
Only if the bore is at least 32 mm. The title's largest candidate bore is 30 mm and the carton label says 25 mm, so a 32 mm bar will not enter either. A 25 mm bore accepts bars up to 25 mm, and the stiffness gain from 16 to 25 mm is already 5.96 times.
How do I know the holder will repeat when I swap bars?
The photographs show direct screw clamping on a split block, with no wedge and no quick-change cartridge. Repeatability then depends on torque discipline and on bore wear, neither of which the page quantifies. Ask for the bore tolerance and the recommended clamp torque.
Frequently asked questions
- What does F68*G42*D30 mean on a CNC turret tool holder?
- It is not a DIN 69880 or ISO 10889 designation. Of the three numbers only 30 matches a standard dimension, the VDI 30 shank diameter. 68 and 42 match no published VDI dimension, so the string cannot be decoded from the standard and has to be confirmed with the seller.
- Is this a VDI 30 or a VDI 40 tool holder?
- The page does not say. D30 suggests VDI 30, but F76 in the same title equals the VDI 60 locating bore, and one of the sibling listings names HAK31100. Measure the shank at the turret face and the locating bore: 30 mm shank with a 38 mm bore is VDI 30, 40 mm with 50 mm is VDI 40.
- Why does centre height matter more than the bore size?
- Because it cannot be adjusted. A bore that is slightly large can be sleeved down; a holder whose centre height is 13 mm off, the step from VDI 30 to VDI 40, cannot be shimmed back on most turrets. One millimetre high already cuts a 10 mm diameter 0.202 mm oversize.
- The carton label says 25. Is the bore 25 mm?
- It is the only bore figure in the eight images, printed on a box behind the holder in image 4, and it reads 25 mm dual use. It is a packing mark, not a drawing. Treat it as evidence that a 25 mm variant exists in this family, and confirm the bore for the specific unit you are buying.
- What is the double water inlet visible in the photographs?
- Two O-ring ports on the front face below the tool bore, which listing 498 describes as a double water inlet. Confirm both are drilled through to the bore and that the O-ring size matches your coolant coupling, because a port that stops short is a port that leaks.
- Can I use a 32 mm boring bar in this holder?
- Only if the bore is at least 32 mm. The title's largest candidate bore is 30 mm and the carton label says 25 mm, so a 32 mm bar will not enter either. A 25 mm bore accepts bars up to 25 mm, and the stiffness gain from 16 to 25 mm is already 5.96 times.
- How do I know the holder will repeat when I swap bars?
- The photographs show direct screw clamping on a split block, with no wedge and no quick-change cartridge. Repeatability then depends on torque discipline and on bore wear, neither of which the page quantifies. Ask for the bore tolerance and the recommended clamp torque.