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Adjustable reamer 34-38,75 NRZe- Artykuły Techniczne - nr. 1
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  • Adjustable reamer 34-38,75 NRZe- Artykuły Techniczne - nr. 1
  • Adjustable reamer 34-38,75 NRZe- Artykuły Techniczne - nr. 1
Varel

Adjustable reamer 34-38.75 NRZe

Varel Varel
846705
€43.70 tax inc.

Net price: €35.53

Brak w magazynie
Brak w magazynie

Call and order: (44) 755-04-05

Description

Adjustable reamer 34-38.75 mm – reamer adjustable to 36 mm

Technical data – HSS blades, shank with square drive for a tap wrench

Technical data
Adjustment range34–38.75 mm
DesignationNRZe to PN
BladesHSS, in inclined grooves
Diameter adjustmenttwo nuts
Shank diameter23.0 mm
Shank square18.3 mm
Overall length292 mm
Blade length96 mm
Drivetap wrench
Adjustable reamer 34-38.75 mm NRZe – dimensional drawing, HSS blades, shank with square drive
Adjustable reamer 34-38.75 mm NRZe – dimensional drawing, HSS blades, shank with square drive

Adjustable reamer 34-38.75 mm The NRZe finishes holes from 34 to 38.75 mm. Set the diameter with two nuts that move the high-speed steel (HSS) blades along inclined grooves in the body. It has a 23 mm shank and a 18.3 mm square, both larger than on the 30-34 mm and 37.5-45 mm reamers. For an 36 mm hole, use a 35.75 mm drill bit with Morse taper MT4. Operate it by hand with a tap wrench fitted over the square on the shank.

Manufacturers design adjustable blade reamers for repair and assembly work. They are useful wherever a hole needs to be fitted to the part at hand. The diameter is then set to the size of the part, rather than to the standard size series of fixed reamers.

Which size to choose: 34-38.75 or 37.5-45 mm

The 37.5-45 mm reamer also covers holes from 37.5 to 38.75 mm. It has a smaller square, 15 mm, and uses a No. 4 tap wrench. This reamer, with a 18.3 mm square, requires a No. 5 tap wrench. Below 34 mm, use the 30-34 mm reamer.

How diameter adjustment works – blades and two nuts

NRZe reamer construction and measuring the diameter setting

The body has inclined grooves around its circumference, each holding an HSS blade. Two nuts, front and rear, retain the blades at both ends. Moving the blades along the grooves moves their cutting edges away from or toward the axis. This changes the cutting diameter over a range of 4.75 mm, from 34 to 38.75 mm. This is why the tool is also called an adjustable reamer.

NRZe adjustable reamer construction – blades in inclined grooves between the front and rear nuts
NRZe adjustable reamer construction – blades in inclined grooves between the front and rear nuts

Adjustment in three steps

First, loosen one nut. Then tighten the other — the blades will move to the new diameter. Finally, lock the blades by tightening the first nut. The rear nut, on the shank side, provides the main clamping force; the front nut is only snugged up. Tighten carefully. Excessive force bows the blades outward and causes the reamer to catch in the hole.

How to measure the set diameter

With an even number of blades, measure the diameter across two opposite blades using a micrometer. With an odd number, a groove lies opposite each blade, so the micrometer will read too low. In this case, use a setting ring or a hole of known diameter. Insert the reamer and expand the blades until they contact the hole wall.

How to ream step by step – tap wrench and clockwise rotation

Guidelines for using an adjustable hand reamer

Insert the reamer into the hole and apply light pressure so the blades engage the wall immediately. The tap wrench must fit the square closely to ensure smooth rotation without jerking. Align the reamer axis with the hole axis. For a longer hole, check the alignment with a square.

Hand reaming in six steps

1
Drill a hole
Use a 35.75 mm drill bit for a 36.0 mm hole. Remove the 0.25 mm allowance in two passes.
2
Set the diameter
Loosen one nut, move the blades with the other, then lock the first nut.
3
Fit the tap wrench
Fit it to the square and align the reamer with the hole axis.
4
Turn clockwise
Turn smoothly with light, even pressure.
5
Withdraw the reamer
Keep turning clockwise, including as the blades leave the hole.
✓
Check the hole
Too tight? Set a larger diameter and make a second pass.
Guidelines based on adjustable reamer manufacturers' instructions.
Hand reaming – adjustable reamer in a tap wrench, clockwise rotation
Hand reaming – adjustable reamer in a tap wrench, clockwise rotation

As the blades emerge from the far end of the hole, resistance drops suddenly. Reduce pressure at this point, but maintain the same turning speed. Otherwise, the reamer will jump through the end of the hole and leave it uneven.

▲
Never turn counterclockwise

Turning counterclockwise in the hole dulls the blades and may chip them. It can also loosen a nut and change the setting. Turn clockwise when withdrawing the tool as well; otherwise, you will scratch the hole wall.

How much material one pass removes

Reaming allowance and drill bit selection

This tool finishes a hole rather than drilling it. It removes a thin layer: from 0.05 to 0.15 mm on the diameter in one pass. A smaller allowance produces a smoother wall. Too little allowance is detrimental, as the blades rub against the wall instead of cutting and become dull faster.

Enlarged view of the reaming allowance – drilled hole and layer removed by the blades
Enlarged view of the reaming allowance – drilled hole and layer removed by the blades

Calculation: 36 mm hole after drilling with a 35.75 mm drill bit

Diametral allowance = finished hole diameter 36.0 mm − drill bit diameter 35.75 mm = 0.25 mm. This exceeds the 0.15 mm that the blades remove in one pass. Set the first pass to 35.9 mm – it will remove 0.15 mm. Set the second to 36.0 mm – it will remove the remaining 0.1 mm.

Finished hole [mm]Drill bit [mm]Diametral allowance [mm]Layer thickness at the wall [mm]Passes
34.534.250.250.1252: set to 34.4, then 34.5
35.034.750.250.1252: set to 34.9, then 35.0
36.035.750.250.1252: set to 35.9, then 36.0
38.037.750.250.1252: set to 37.9, then 38.0

The drill bits offered from 32 mm upward have Morse taper MT4. In this range, they are available in 0.25 mm increments, so the allowance is 0.25 mm. Remove it in two passes: 0.15 and 0.1 mm.

Tap wrench and lubrication – what to prepare

Tap wrench for a 18.3 mm square and oil suited to the material

Tap wrench No. 5

The shank square measures 18.3 mm. Select an adjustable tap wrench to DIN 1814, size No. 5. It accommodates squares from 7 to 20 mm and fits M12–M33 taps.

With oil or dry

Workpiece materialLubrication
Steel and cast steelcutting oil or emulsion
Aluminum alloyscutting oil or emulsion
Gray and malleable cast irondry
Bronze and brassdry

Remove chips from the reamer after use. Before adjusting the blades, also clean the body grooves so the blades move evenly.

Adjustable reamer 34-38.75 mm The NRZe has a 23 mm shank and a 18.3 mm square that fits a No. 5 tap wrench. The reamer is 292 mm long, and its blades are 96 mm long. Prepare a 36 mm hole with a 35.75 mm drill bit with Morse taper MT4. Ream twice: to 35.9 and 36.0 mm, always turning clockwise.

Questions about drill bits, size selection, and operation

Frequently asked questions about hand reaming

Drill it with a 35.75 mm drill bit with Morse taper MT4. Remove the 0.25 mm allowance in two passes: to 35.9 and 36.0 mm.

Both cover a 38 mm hole. The 34-38.75 mm reamer has a 18.3 mm square and uses a No. 5 tap wrench. The 37.5-45 mm reamer has a 15 mm square and uses a No. 4 tap wrench.

Clockwise, just as when reaming. Clockwise rotation protects the blades and the hole wall. It also keeps the nuts in place, so the setting does not change.

Yes, at very low speed and with plenty of oil. At high speed, the hole may end up larger than the setting. Using a tap wrench provides the best control.

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Adjustable reamer 34-38.75 NRZe

Adjustable reamer 34-38.75 NRZe

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