- 98% satisfied customers
- 72h delivery
- 30 dni na zwrot
Description
Diameter26 mm
Drilling depth78 mm (3×D)
Inserts2 × WCMT 050308
Hole tolerance0/+0.25 mm
Ø26 indexable drill – 3×D insert drill
Varel SD26-78-C32: drilling depth 78 mm, shank 32 mm, WCMT 050308 inserts
| Technical data | |
|---|---|
| Drilling diameter | 26 mm |
| Drilling depth l1 | 78 mm (3×D) |
| Length to flange l2 | 104 mm |
| Shank length l3 | 60 mm |
| Overall length L | 155 mm |
| Shank diameter d1 | 32 mm, Weldon flat |
| Flange diameter d2 | 34 mm |
| Inserts | 2 × WCMT 050308 |
| Insert screw | M3x7, Torx T8 |
| Coolant supply | internal, 2 channels |
| Hole tolerance | 0/+0.25 mm |
| Varel designation | SD26-78-C32 |
Ø26 indexable drill Varel drills holes with a diameter of 26 mm and a depth of up to 78 mm, or three diameters. According to the drill size table in PN-86/M-59601, this is the tap drill size for M28x2 and M27x1 fine threads. Instead of a steel cutting edge, it has two replaceable WCMT 050308 cemented carbide inserts. A dull edge is replaced by indexing the insert, while the body remains in service. The drill operates on machining centers and CNC lathes.
Coolant flows through two channels inside the drill directly beneath the inserts. It flushes chips out of the hole and cools the cutting edges. The 32 mm shank with a Weldon flat is secured in a holder with a 32 mm bore and a clamping screw. This type of indexable drill is also called an insert drill or U-drill.
Drilling depth of 78 mm and hole bottom shape
How deep the drill can drill and what remains at the bottom
The flutes end 78 mm from the drill face. Up to this depth, chips have a path out of the hole. The Varel catalog therefore specifies a drilling depth of 3×D, or 3 × 26 mm = 78 mm. For holes up to 130 mm deep, use the Ø26 5D indexable drill.
The hole bottom does not have the cone left by a 118° twist drill. It is nearly flat, with slight undulations left by the two inserts. Only a low cone remains at the center.
The resulting hole diameter ranges from 26.00 to 26.25 mm. This is the range allowed by the Varel catalog for 2×D and 3×D drills. Holes requiring a specified fit are reamed or bored after drilling.
How the two WCMT 050308 inserts work
Center insert, peripheral insert and self-centering
Both inserts sit on the drill face: the center insert near the axis and the peripheral insert at the edge of the body. The flutes guide chips from the inserts toward the shank.
The same WCMT 050308 insert is used in both pockets. The center insert cuts from the hole axis, while the peripheral insert cuts the 26 mm diameter. Their cutting edges overlap, so no uncut ring remains at the bottom.
Cutting speed increases from zero at the axis to its maximum at the periphery. Near the axis, the insert pushes material aside more than it cuts it. As a result, the center insert is more prone to chipping, while the peripheral insert wears due to heat. Check both inserts whenever indexing the cutting edges.
The two inserts guide the drill along its axis, so spot drilling is not required. Drilling starts directly in solid material. A pilot hole in the workpiece must not exceed 6.5 mm, or 1/4 of the drill diameter. A larger hole pulls the drill off-axis.
The insert designation is interpreted according to ISO 1832. W denotes a 80° trigon with three cutting edges. C indicates a 7° clearance angle, M the tolerance class, and T a screw hole and chip breaker. 05 indicates the insert size (inscribed circle 7.94 mm), 03 the thickness of 3.18 mm, and 08 the corner radius of 0.8 mm. Our store offers the Horn WCMT 050308 insert for indexable drills.
After loosening the screw, rotate the insert in its pocket by 120° to bring the next cutting edge into use. Each WCMT 050308 insert has three edges, so a set of two inserts provides three indexing positions.
Changing the insert cutting edge
1Loosening the screw
Key: Torx T8
2Indexing the insert
Rotation: 120°
3Cleaning the insert seat
Chips: to be removed
4Tightening the screw
Screw: M3x7
Included: body, Torx T8 key and two M3x7 screws.
Drilling on a machining center and CNC lathe
Coolant, axis alignment and difficult material entry
Machining center – through-spindle coolant from 4 bar
Coolant is supplied through the spindle and drill at a pressure of at least approximately 4 bar. This is the value specified in the Varel catalog for 2×D and 3×D drills. Mount the drill in a rigid holder with minimal runout relative to the spindle.
▲
External coolant: 39 mm in a single pass, deeper holes with retraction
With externally supplied coolant, the drill can drill up to 1.5 × 26 mm = 39 mm in a single pass. For deeper holes, retract the drill every few millimeters to flush out chips.
CNC lathe – coaxial alignment within 0.03 mm
On a lathe, the drill remains stationary in the turret while the workpiece rotates. The drill axis must align with the spindle axis within 0.03 mm.
Setup on a lathe
1Test bar
Bar: Drill Ø and length
2Runout measurement
Indicator: on the chuck, 360° rotation
3Axis adjustment
Deviation: below 0.03 mm
4Insert positioning
Peripheral insert: parallel to the X axis
Peripheral insert on the outer side of the turret; check axis alignment again after a lathe collision.
▲
A disc is ejected at breakthrough
When drilling through, a disc of material is ejected from the bottom of the workpiece at high speed. Keep the lathe guard closed throughout drilling.
Difficult entry – inclined, concave and uneven surfaces
It is best to drill into a surface perpendicular to the drill axis. On other surfaces, the inserts are loaded unevenly and the drill moves off-axis. In this case, reduce the feed to 1/3 of the recommended value.
Convex surface
The drill center contacts the material first. Normal feed.
Inclination over 2°
One insert enters earlier and wears faster. Feed 1/3.
Concave surface
The drill moves off-center. Feed 1/3.
On uneven surfaces, reduce the feed at entry and breakthrough to protect the insert from chipping. Drill intersecting holes at approximately 1/3 of the recommended feed.
Drilling symptoms and adjustments
| Symptom | Cause | What to adjust |
|---|---|---|
| Chipped center insert edge | Cutting speed drops to zero at the axis and the insert pushes material aside | Lower feed at entry and breakthrough, tougher insert grade |
| Rapid peripheral insert wear | Cutting speed and temperature are highest at the periphery | Cutting speed at the lower end of the range, through-tool coolant |
| Drill moves off-axis | Inclined or concave surface, pilot hole larger than 6.5 mm | Feed at 1/3 of the recommended value on entry, pilot hole up to 6.5 mm |
| Chips accumulate in the flutes | External coolant at depths greater than 39 mm or pressure below 4 bar | Through-tool coolant from 4 bar; use peck drilling with external coolant |
| Hole wider than 26.25 mm | Holder runout, axis misalignment over 0.03 mm on a lathe | Rigid holder, adjust turret axis alignment using an indicator |
Cutting data for steel, stainless steel and cast iron
Cutting speed, spindle speed and feed – starting values
The table lists the lower cutting speed limit from the Varel catalog. Feed per revolution for the WCMT 050308 insert ranges from 0.06 to 0.14 mm. The starting value is 0.07 mm; then gradually increase the feed while monitoring the chips.
| Workpiece material | Cutting speed vc [m/min] | Spindle speed [rpm] | Feed f [mm/rev] | Feed rate [mm/min] |
|---|---|---|---|---|
| P Low-carbon steel (up to 0.3% C) | 160 | 1950 | 0.07 | 136 |
| P Carbon steel (from 0.3% C) | 150 | 1830 | 0.07 | 128 |
| P Alloy steel up to 300 HB | 120 | 1460 | 0.07 | 102 |
| P Alloy steel above 300 HB | 100 | 1220 | 0.07 | 85 |
| M Stainless steel | 80 | 970 | 0.07 | 67 |
| K Gray cast iron | 130 | 1590 | 0.07 | 111 |
| K Ductile cast iron | 100 | 1220 | 0.07 | 85 |
Spindle speed and feed calculation – alloy steel up to 300 HB
Spindle speed = 1000 × cutting speed 120 m/min ÷ (3.14 × diameter 26 mm) ≈ 1470 rpm – set the machine to 1460. Feed rate = 1460 rpm × feed 0.07 mm/rev ≈ 102 mm/min. A hole 78 mm deep takes approximately 0.8 minutes (78 ÷ 102). When entering an inclined surface, reduce the feed to approximately 0.02 mm/rev.
Ø26 indexable drill Varel SD26-78-C32 drills holes with a diameter of 26 mm and a depth of up to 78 mm without spot drilling. It uses two WCMT 050308 inserts, each with three cutting edges. Coolant flows through the drill directly beneath the inserts and flushes out chips. The resulting hole is within a tolerance of 0/+0.25 mm, and its bottom is nearly flat. The body with a 32 mm shank operates on machining centers and CNC lathes.
Questions about inserts, spot drilling and the hole bottom
Included items, centering, lathe use, hole shape and diameter
Two WCMT 050308 inserts – the same insert in the center and peripheral pockets. Our store offers the Horn WCMT 050308 insert for indexable drills. The body comes with a Torx T8 key and two M3x7 screws.
The drill centers itself using two inserts, so drilling starts directly in solid material. A pilot hole in the workpiece must not exceed 6.5 mm. A larger hole pulls the drill off-axis.
Yes, the drill remains stationary in the turret while the workpiece rotates. The drill axis must align with the spindle axis within 0.03 mm. A disc of material is ejected at breakthrough, so keep the lathe guard closed.
The bottom is nearly flat, without the 118° cone left by a twist drill. The two inserts leave slight undulations. A low cone remains at the center.
The hole diameter ranges from 26.00 to 26.25 mm – the range allowed by the Varel catalog for 2×D and 3×D drills. The result depends on machine rigidity and holder runout. Holes requiring a specified fit are reamed or bored after drilling.
Product accessories
Carbide insert WCMX 050308 H6310 Horn
Reference: 0000011224 In stock > 10 items
€3.68
€4.53 brutto
Reviews
No customer reviews for the moment.
Shipping
All orders are delivered by courier company GLS. For orders exceeding 369 PLN gross shipping is FREE
| Courier GLS | Przelew24 / Prepayment | 14,76 zł gross | Delivery time 1 working day |
| Courier GLS | Cash on delivery | 17,26 zł gross | Lead time 1 working day |
Recommended for you
Viewed products
This website uses its own and third-party cookies to improve our services and show you advertising related to your preferences by analyzing your browsing habits. To give your consent to its use, press the Accept button.
Cookie preferences
Functional cookiesTechnical
Functional cookies are strictly necessary to provide the services of the shop, as well as for its proper functioning, so it is not possible to refuse their use. They allow the user to browse through our website and use the different options or services that exist on it.
Advertising Cookies
These are cookies that collect information about the advertisements shown to users of the website. They can be anonymous, if they only collect information about the advertising spaces shown without identifying the user, or personalised, if they collect personal information about the user of the shop by a third party, for the personalisation of these advertising spaces.
Analytics cookies
Collect information about the user's browsing experience in the shop, usually anonymously, although sometimes they also allow the user to be uniquely and unequivocally identified in order to obtain reports on the user's interests in the products or services offered by the shop.