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Friday, April 20, 2018

CMM Fixturing Measurement Techniques

Does CMM correct a bad fixturing of a workpiece?

Does CMM correct the impact that a bad fixturing has on GD&T's, lengths, diameters and angles ?

I think, the part fixturing and part alignment into the fixture is the main factor in CMM incorrect measurements. If we define the part fixturing and alignment incorrectly as a concept the CMM will be used incorrectly. 

If the CMM result of a trueposition of a feature to datum -A- is out of the tolerance can the CMM correct the true position if it the datum A is measured as a cylinder and the part is 3 degrees skewed from being parallel to the CMM axis. I never have assumed that the CMM corrects the errors of fixturing, and the part can be measured without a precise fixturing/alignment.

First question I will ask is what’s our benefit if the CMM does that?

We do not need a precise fixturing-alignment of the part into a fixture and consequently we save some time/cost on this.

Practically, how it is going to work when we measure parts on CMM and we see a red CMM result?

If we take for granted what we are being told that CMM corrects the errors of fixturing-alignment of the part, we need to know the answer of some very simple questions.

First, I would like to know how much error of fixturing in angles or .xxx” (in numbers) the CMM corrects? 

Secondly, the CMM corrects that for all kind of dimensions and all GD&T’s or only for some of them? 
As we know, there are 2-d and 3-d dimensions, simple features and sphere features, and the roundness is not the same as the perpendicularity, or the parallelism as the true position. The CMM may correct the perpendicularity, or parallelism when there are errors of fixturing but may not correct the fixturing errors for the the roundness or the true position of cylindrical features.

On the other end, if there is not an “error correcting” number, for example up to 3° from being parallel to Z axis, or .005” in Z direction, or a list of GD&T’s how can we accept assumption that CMM corrects the errors of fixturing?

When we use a CMM program how we are going to understand the borders that the CMM corrects or does not correct the errors of fixturing-alignment of the part and to react, to fix it in order to get e good measurement? 

We want to know that number with the simple purpose to apply that knowledge and having accuracy and precision in measurements.

What CMM does if the work piece is aligned wrongly  -0.2” in Z direction and 3° skewed from the Z axis?

Calypso knows the old position of the workpiece from the base alignment when is defined the workpiece alignment, when the coordinate system is established by probing physically the part, if you used the standard method to define the workpiece alignment, the 3 known steps of the part alignment, level-rotation-origin.

First time Calypso will scan the first feature of the base alignment according to the old data position. For example, if the first feature is a bore with the axis positioned perpendicular to Z axis, Calypso on the first time will touch only half of the bore and you can see how the probe will scan the air for the other half. After Calypso gets the new points Calypso will scan the same feature again, but this time correctly because the new features position now is recognized and being corrected. The old position is overwritten. So, Calypso corrects this kind of fixturing errors.

Practically, there will 
always be an error of fixturing, it does not matter what kind of base alignment you are using, automatic, or manual alignment or start alignment, Calypso will always correct the old alignment to a new alignment.

Calypso corrects the workpiece to a new position, but Calypso cannot correct that 3° angle of a bad fixturing. The angle will still be 3° to the CMM axis and it will have an impact, for example, on the roundness of a bore which could be as bad as .002” or more when the actual Roundness is .0003. 

Without a good fixturing it is not possible of forming datum planes or axes from their high point contact, right angle, distance, circular form, orientation, location, center axis of the feature. No good fixturing may form incorrectly datum frames. 
No good fixturing will also cause the probe measurements will not be taken enough perpendicular or parallel to the probe body which will produce errors and give results that are less repeatable and accurate.

Use always 3-jaws-clamping devices, vises, magnet and tall pins to set the part when it is being programmed on CMM. A good fixturing allows the datums to be repeatable.

From my experience a bad fixturing has a huge impact on GD&T's, a medium impact on lengths and diameters.

Tuesday, November 14, 2017

GR&R Studies

It’s all about the measurement variations and correcting the factors that contribute on it.

Measurement variations can come from three main sources: the person using the gage, person to person and part to part. It is also the gage itself a factor.

MSA studies exist to discover and quantify the amount of variation coming from these different sources, so that corrective action may be taken if necessary.

There are too many formulas of Gr&R studies. It depends from our intention:

1) To discover the amount of variation coming from three main sources.

We need the data of one dimension-measurements(a) of three persons(b) for 10 parts(c), taken from Measurement Systems Analysis Reference Manual, 3rd edition (Chrysler, Ford, General Motors Supplier Quality Requirements Task Force). Ten parts were selected that represent the expected range of the process variation.

Three operators measure the ten parts, three times per part, in a random order.

2) To examine the accuracy of a gauge, how accurate is a gauge when compared to a reference value and if it has the same accuracy across all reference values.

Gage repeatability and reproducibility studies determine how much of your observed process variation is due to measurement system variation.

Minitab provides two main methods for Gage R&R Crossed: X and R, and ANOVA.

The X and R method breaks down the overall variation into three categories: part-to-part, repeatability, and reproducibility.

The ANOVA method goes one step further and breaks down reproducibility into its operator, and operator by part components whereas the X and R method does not.

How to interpret the the Gr&R results.

The % Study/Var column shows the Total Gage R&R. Less than 10% -the measurement system is acceptable.

Saturday, June 18, 2016

Minor diameter of spline as the spline datum

Is it possible to use the minor diameter of a spline as  a  datum when the print requires to check the GD&T’s of other features to a spline datum?

In this days, it is known that the Spline Gauges are the best inspection tools to check the splines. Spline gauges have an advantage over old methods of checking spline dimensions because the use of spline gauges not only ensure the quickest process for acceptance, which means also less timing cost, but also eliminates the need to inspect the profiles with old ways such as three pins method, pin+dial indicator methods,etc.

 By using ‘GO’ and ‘NO GO’ spline gauges and plain ‘GO’ and ‘NO GO’  we ensure:

1    1)  ‘GO’ spline plug gauge checks the profile flank , the equally spiced angles  for all teeth, the extension of the root radius to the pitch circle diameter, pitch circle diameter and the runout of pitch circle diameter to major diameter of spline.

     2)  ‘NO GO’ spline plug checks the major diameter and space tooth width.

3   3)    GO’ and ‘NO GO’ plain gauges check the minor diameter of spline.

So, all gauges  ensure all dimension and fitting of the spline and among other dimensions also that the position of 3 min-pitch-max diameters to each other are within their tolerances. 

As a conclusion, when the GO/NO-GO spline gauges and plain plug gauges accept the spline it is possible to use the minor diameter of spline as a datum when the print requires to check the GD&T’s of other features to a spline datum. 

Wednesday, October 7, 2015

Pre-Plate pitch diameters, major diameters, and minor diameters of thread rings, thread plugs, and plug gauges.

The rules for determining Pre-Plate pitch diameters, major diameters, and minor diameters of thread rings, thread plugs, and plug  gauges are as follows:

To determine Pre-Plating dimensions for external threaded parts: 

For external threads subtract the max plating thickness from the high limit Pitch Diameter, and then subtract the minimum plating from the low limit Pitch Diameter  

For the minor and major diameters reduce the maximum diameters by half the maximum plating and reduce minimum diameter by half the minimum plating.   

To determine Pre-Plating dimensions for internal threaded parts: 

For internal threads add the max plating thickness to the low limit of the Pitch Diameter, and then add the minimum plating thickness to the high limit of the Pitch Diameter.  For minor and major diameters increase the minimum minor diameters by half the maximum plating and increase the maximum minor diameter by half the minimum plating. 

To determine Pre-Plating dimensions for thread ring gauges: 

For thread ring gauges subtract the max plating thickness from the Pitch Diameter of the Go thread ring gauge. Then subtract the minimum plating from the Pitch Diameter of the No-Go thread ring gauge. For the minor diameter reduce the Go ring minor diameter by half the maximum plating and reduce the No Go ring minor diameter by half the minimum plating. 

To determine pre plating dimensions for thread plug gages: 

For thread plug gauges add the max plating thickness to the Pitch Diameter of the Go thread plug gauge.  Add the minimum plating thickness to the Pitch Diameter of the No-Go thread plug gauge. Increase the major diameter of the Go thread plug by half the maximum plating and increase the No Go thread plug major diameter by half the minimum plating. 

Example for Thread Plug Gage:

Plating of .0002” - .0003” allowance per side multiple x 4
.0003 x 4 = .0012” Max
.0002 x 4 = .0008” Min

½ - 20 UNF 2B Pre-Plate

Basic standard Go Pitch Diameter = .4675” + .0012” = .4687” Go  Pre-Plate Pitch diameter.
Basic standard No Go Pitch Diameter = .4731” + .0008” = .4739” No Go Pre-Plate Pitch Diameter.
Basic standard Go Major Diameter = .5000” + .0006” = .5006” Go Pre-Plate Major Diameter.
Basic standard No Go Major Diameter = .4948” + .0004” = .4952” No Go Pre-Plate Major Diameter.

Example for Thread Ring gages:

Plating of .0002” - .0003” allowance per side multiple x 4

.0003 x 4 = .0012” Max
.0002 x 4 = .0008” Min
.0003 x 4 = .0012” Max
.0002 x 4 = .0008” Min

½ - 20 UNF 2A Pre-Plate

Basic standard Go Pitch Diameter = .4662” - .0012” = .4650” Go Pre-Plate Pitch Diameter
Basic standard No Go Pitch Diameter = .4619” - .0008” = .4611” No Go Pre-Plate Pitch Diameter
Basic standard Go Minor Diameter = .4446” - .0006” = .4440” Go  Pre Plate Minor Diameter.
Basic standard No Go Minor Diameter = .4511” - .0004” = .4507” No Go Pre-Plate Minor Diameter.

If no minimum and maximum plating thickness is given, then the given plating thickness is considered nominal or minimum plus 50% to determine maximum plating.

Monday, February 9, 2015

Number of turns on the thread gauge

Calculating the number of turns on the thread gauge for the thread Size M10 x 1-6H.

The number of turns on thread gauge:

Length of threads: 0.402 ± .015: A length without threads is 0.158- Not given on the picture, and the diameter of countersink is 0.435 / 0.437 x 90°

Thread Size: M10 x 1-6H

I. Minimum of turns
a) Convert the pitch: 1 / 25.4= 0.03937”
b) Minimum of turns:
1) Calculating first the threaded material length when the 0.402” dimension is on the minimum of its tolerance and the 0.158” dimension is in on the maximum of its tolerance:

L1 = (0402 - 0.015) - (0.158+.004)=0.225”

2) Calculating the length without threads.

From the dimension of countersink 0.435 / 0.439. Nominal diameter of countersink is 0.437
From the dimension of the M10-1, the max diameter for internal threads is 10 mm-converted in inch 0.393”.

3) Calculating:

Minimum full length thread=L1-H=0.225 - 0.022= 0.203
Number of turns for the minimum full threads length: 0.203 / 0.0393=5.1653 turns

c) Maximum of turns

Calculating the opposite case when the 0.402 is on the maximum of its tolerance and the 0.158 dimension is on the min of its tolerance:

L 2= (0.402+0.015)-(0.158- 0.004)=0.263”

L max full thread=L2-H= 0.263 - 0.022= .241

Number of turns for the maximum full threads length: 0.241 / 0.0393=6.13 turns

Number of turns: 5.16 turns minimum / 6.13 turns maximum

Friday, December 26, 2014

Nazi-Communist Vladimir Putin #2

I am readdressing this topic again because the actions of Putin's intolerance are escalating.

So far, Nazi-Communist Vladimir Putin seems to feel a grande nostalgia for the time when Russia he thinks had dignity. It is obvious Putin is escalating the propaganda in order that Russia will regain that degnity. Russian people once were a big proud nation, and his beloved Russia was the head of the socialist camp.

The propaganda of Putin is a combination of two elements: fear from an enemy and incite ordinary people to tolerate mass violence. Putin is proposing a granfalloon situation naming NATO's military buildup near its border as the main military threat and Russia could use nuclear weapons.

Now, NATO is to be blame for the all Russia problems. Crimea is a legal part of Ukraine, a sovereign nation. Putin knew everything about Hitler and Czechoslovakia but he invaded Crimea. In the annexation of Crimea Putin crossed the line. Every dictator has had the first step and his new doctrine. His new doctrine is portraying NATO as a enemy of Russia because NATO is the only obstacle in the way to his beloved Russia.

First step of Hitler was when he took over Czechoslovakia because of "ethnic Germans"-"not being treating right"-"protect my people". So, those labels "ethnic Germans"-"not being treating right"-"protect my people". were called before invading Czechoslovakia. The people tend to select that "The German military intervention is to defend ethnic Germans and mass violence is justified ", and after Czechoslovakia he attacked Poland which was the second country to be invaded by Hitler and sparked World War II.

Hitler invaded:

The Netherlands
USSR: Russia, Ukraine and Crimea.

There is only one difference between. At that time of Hitler NATO did not exist. 

Monday, November 24, 2014


Do the linguists know that ἀδάμας – adámas "unbreakable" of the ancient Greek exists in Albanian in the form of "pa ndam" which means "undivided"?

Most of what is written about Albanian are lies.

The Albanian language is generalized by modern scholars based on paranoid interpretations mostly rooted on biases. Most of what is written from scholars about Albanian is an evidence of the narcissistic literature. Most of Scholars did and keep doing the same mistake that common people do, jumping and staying in a big bandwagon.

Linguistics scholars keep doing the same thing first scholars have been paid by elites for: practice untruthfulness under the protective veneer of the name “scholar”.

νῶε νώ , νῶε ,A.v. ἐγώ ", Alb. unë

μέσ ,Αιολεις ;- Alb. mes.

πᾶν (pan, “whole, all”) , Alb. paanë

ἰσόω, νῆσος , Alb. njisoj, iso, soj

δαίτης, Alb. n`dajtës.

χαρι, χ(α)ρι, χρυ, χρυσ, χρυσός, Alb. ar ;gold'.

βυκῶσθαι 'to be swollen', Homeric βυκτάων 'blowing' , Alb. bukos 'swell'

εξία , Alb.është_ia", εὐεξία 'good habit of body, good health', Alb. mireqenja

σχιστος 'easy to split', Alb.'v.shqyej'

αρασσειν, Alb. të rrahësh.

θάλεια 'bloom, flower', Alb.'-gjallia'

Δηώ, Alb. dheu.

δυσγνοιαν, Alb. dysh- njohja

χυτος 'easily diffused', Alb. zhytes.

κηλος 'easily burning' , Alb. 'kallës' , kall 'burn'

αθώα, α-θώα, Alb. pa thua, pa thonj (thonj të prerë).

τίθημι (tithēmi) future: θήσω aorist: ἔθηκα perfect: τέθηκα perfect m/p: τέθειμαι aorist passive: ἐτέθη, Alb. vendos

θερεία, θέρος' summer'; Alb. vere.

ἀριίηθεν ,' golden,shiny place'; Alb. vend i arte

ὕπερ-'upper' ; Alb. hypur

ὑψό , Alb. hypes

Χωλός, Alb. çâlò, çôlò.

νῶροψ , flashing, ,νῶροψ A.flashing, Il.2.578; later simply, bright, Alb. sy ‘eye’ + nur 'shine'.

Φῂς + λεω 'speak' φαμί 'say'; Alb. flas

ἐσχατιῇ , ' extension,length' Alb. zgjat,'e`zgjatija ' zgjatimi'

χήρα, Alb. i gjorë.

χανδάνω, Alb., gjëndem.

βάζω speak, say, Alb. bëzaj.

τραῦμα , ατος, τό, Ion. τρῶμα , Dor. also τρῶμα , I. "wound, hurt," Alb. rrah, rraf 'beat'.

κρεξ =' κορυφαια' tuft on the crown of the head' ; Alb. kreshtë.

κεραυνος, Alb. rrufe 'lightning'.

ἤχημα 'sound', Alb. vikamë f. krahin. britmë; thirrje; vigmë.

ῥώξ (B), ῥωγός,ῥάξ , ῥα_γός, ἡ, Ion. and later Gr. ῥώξ (v. ῥώξ (B)), grape; Alb. rrushtë, rrush ,

γρύξ: τοῦ ὄνυχος, Hsch.ὄνυξ 'talons, claws', Alb. grusht.

λίξ = sickness, disease, plague ; Alb. ligeshti.

λυπη, λυπρη ,’beg’, Alb. lypi, Alb. geg. lypni, Alb. tosk lypri.

βύσταξ , μύσταξ ' upper lip' Alb. buzë 'lip'.

ὦσις pushing,; ὡσιωμένως ; ὠσμή; Alb. ush (pasth).

επαρσις, Alb. epërsi

ναννη "mother" ; Alb. nëne,nanë.

αμμας " mother" ; Alb. amë, e ama, e ëma.

κεμποσ "light footed' kembe lehte, Alb. kembe 'foot', këmbosh

Hom.:—ᾐών,ἤια(λύκων ἤια )" food for wolves' ; provisions, food,; alb.dialect heja 'eating'.

Hom.ᾐών,ἤια, ἤι_α, ᾖα = Alb. heja.

oino, iven Doric ,'wine'; Alb. vene,vere

λοπός ‘peel, cortex, skin',  Alb. rrobe.

στάμνος 'earthen jar',  Alb. shtambë.

Homer ἐνδέω, 'bind or tie in or on', ‘entangle,; Alb. end.

γλωσσα, glossa, Alb.gjuhe,guha, gua.

ἐτήτυμος (cf. ἔτυμος, ἐτεός): true, truthful, real; Alb. jeton, të jetë-të, me të-jetë, jetisht.

υσχρος, alb. ushkur.

ἐπανα-σπείρω 'sow again', σπείρω ",Alb. biroj, zhbiroj ‘perforate’.

ἐπ-ειλέω 'wind up'; ἐπαν-ειλέω 'unroll' ;ειλέω, Alb. sjell, "spin".

ἐπι-βόλαιον 'covering, wrapper', Alb. mbuloj, n-mbulese.

ἐπι-δέω,'want' ; Alb. due, dua.

ἐπί -φρουρος 'keeping watch over', Alb. pruj,ruaj.

ἐπι-κοπή"cutting"; Alb. coptoj.

ἐπι-λιπής, 'wanting', Alb. lyp.

κάδος, Alb. kade.

βαλβισ, Alb. valvit.

σαλάγη , noise, outcry , Alb. zallahi

σεῖα, seia.  'I persecuted' (Attic ἐδίωξα edioxa) (Cf.Homeric seuō move quickly,chase), Alb. zë, përzë

τραυμα, Alb. të vrame~t'vram-e.

ephoroi 'high officials at Sparta', Alb. epror.

πλήθα, assembly, Alb. m-bledhje.

τιτώ, day ,τι_τώ , οῦς, ἡ, A. = ἡμέρα, day, Alb. ditë.

παρθενα ''virginal’, Alb. e-bardhë.

was doric, Alb. vesh.

ᾠόν,egg;ὤεον , poetic for ᾠόν ,an egg, ὤβεα ôbea. eggs (Attic ὠά ôa );ὤβεον ‘egg’, Alb. ve, vo, vezë.

τάγανα tagana (Attic tauta) these things", Alb (ke)to gjana"

Β α ρ θ ε ι• yένος ιθαγενών,  Alb. i bardhe.

ξηρά ,dry land, Alb. thaj ‘dry.

χαρά χαρη, Alb. hare

χέω, Alb. derdh.

καμπυλιρ, καμπ ‘foot’+υλιρ ‘olive’, Alb. këmbë ulliri.

χρίω, 'touch the surface of a body slightly', Alb. kruaj.

κωθα, Alb. kupë.

σερμοι Laced. 'fire', Alb.zerm, zjarm, zjarr.

σαννάκιον 'cup' , Alb. çanak.

σαράβαρα 'loose trousers', Alb. shallvare.

τύπανον 'drum', Alb. tupan.

κέλυφος 'sheath', Alb. kellëf, klluf

πηδάω 'leap, spring', , Alb. pejdah

κουβάς 'bucket, pail', Alb. kovë

κελέβη , pan, Theocr., Alb. çerep

δύνω , Alb. dial. dun/

κάτω 'down, below', Alb. katua.

πλέκω 'I weave together', Alb. pleks.

κλών , Alb. krane, krande.

ἥσσων 'weaker, lesser', Alb. i shuar.

ἥττημ-α, Alb. i/e thime(i/e thyer).

ἀγαλλιάω, Alb. gjalloj.

λοιπός Ab. lë pas, ku λοιπός=λοι(la) + πός(pas).

κυτίς 'small chest, trunk', Alb. kuti.

κηδεία ‘care’, Alb. kujdes'.

κακο-καρπία 'bearing bad', Alb. keq-kaplloj.

κατα-ληρέω 'lose by idle talking', ληρέω, Alb. liroj 'lose'.

καρ-χαρέος, Alb. kre-sharre

καρχαρίας 'shark', Alb. kre-sharrues

κατα-χύδην 'pouring down', Alb. hudh, hedh

κερχαλέος 'rough, hoarse'. Alb. gerxh

αή 'blowing hard', Alb. fryj, aj

χορδή , guts, tripe. Alb. kordhez

γάθω , πολυγηθής 'much-cheering, delightful, gladsome', Alb. gezoj

σκίρτημα 'bound, leap' /σκίρτησις bounding, leaping/ἐπισκίρτημα spring, bound, Alb. kercej

πλήθα assembly, Alb. m+bledhje

βλεπειν(βλεπω) Alb. vrej(vërrej):

ἄ-σκυλτος,Alb. shkul.

κανθάρεως , Alb. kacarrem

Bερ-ώ, Alb. bjerë(bie)

ὕμν-ος , Alb. hymn.

βρυχηθμος, Alb. britmë.

Kου-ζος, Alb. gojë+zan

βρό, βρoότ, βροτές. Alb. vrôtës/vrôsës; vv. vrôhe/vrôhô, vrâhḕt/vrôhôt (ο≠ό, μετ. βροτός*<βρο_ότ_ς).

αμελγειν 'milk', Alb. amel (të mjelësh)

γραφία, Alb. gervish

μικρ-ός < αρβ, Alb. micërr «» *mickërr, *mikërr.

σκίμπτω, σκήμπτω 'overthrow',  Alb. shuaj, fik.

φιλειν,  Alb. përfill.

ψαίστωρ , ψάω ,sweep,sweeper, Alb. fshires, fshaj, fshi.

ξ , 'to be poured over', Alb. shti, shto.

ξεστίζω ,polish. Alb. sheshoj.

ἐξάγω LSJ, lead out, lead away; Alb. jashte-shko (shko'go').

ἐξ-ορθόω LSJ, 'set upright'; Alb .jashte-urdhnoj.

μέδομαι 'to provide for, think on, be mindful of', Alb. mejtohem.

ταράσσω 'stir, trouble', Alb. trazoj, trazovaç.

θυμιάω 'burn so as to produce smoke', Alb. tymoj.

ποι, Alb.boj.

δηλώσω, Alb. diellzoj.

παράνοια, Alb. para + njohja.

ἐλεήμων, Alb. lëmontì, lëmoshë.

τέφρὴ, Alb. te frysh, me fry

mneia, menia, Alb. geg menia

κώρα , Doric, Theoc.6.36, Alb. korra ; cropping

θέρος (theros) (genitive θέρεος or θέρους); n, third declension; Alb. ther

ηλαχάτη 'shaken with the wind', Alb. Shalakat, hallakat

κάρφη ξυλα λεπτά χαϊ ξηρά –Alb. Shkarpë

σκέπαρνον ; the Homeric passages, Eng. carpenter's axe for hewing and smoothing the trunks of 

trees, adze, Alb. sqepar . Derivation of σκέπ, Alb.skep (sqep) 'beak'.

κόπανον ξΰλον όργανον πληκτικόν , Alb. Kopan.

κοπίς ,μερϊς 'piece', Alb. copë.

άρδάλους είκαίους''purposeless 2. of persons, rash, hasty, Alb. Hardall, hardallosur

κόρυνθος μάζης ψωμος , Alb. Krunde (therrime buke')

αuς. αυτός Κρήτες καϊ Λάκωνες, Alb. ay,ai

κοσύμβη 'shepherd's coat', Alb. gozhup

σμάω wipe, Alb. dial. mshaj (fshij).

φάρυγξ 'throat', Alb. grykë.

άραιόν – ά+ραιόν /not heavy, Alb. rand 'heavy'

Demetra 'mother earth', Δηώ (Callim.)Δημήτηρ ; Δμήτειρα '' γη γεννήτρια = Alb. dhe * earth 

λοχία, Alb. lokia (grandpa from the father side)

κλαῖον δὲ λιγέως They cried shrilly ,Alb. qan me ligje, Alb. Tzam and Arberesh *klaj/ cry

κλαῖε δ' ὅ γε λιγέως - He was weeping loudly – Alb. qan me te madhe (ligje);

Μοῦσα λίγεια”; of articulate sounds, clear-voiced, Alb. ligjëroj